[QUOTE=GP2;443923]Someone (not me) found a big one, the first known factor of [URL="http://www.mersenne.org/report_exponent/?exp_lo=5879&full=1"]M5879[/URL]:

3381116440321017148580653633902983992991015840485797617951

58 digits, 192 bits.[/QUOTE]
It's my the best result

M5879
 

I noticed that result also.
Impressive.
Plenty of bits.

P-1 found a factor in stage #2, B1=665000, B2=12635000.
UID: Jwb52z/Clay, M79505071 has a factor: 13162456229681530231421707433 (P-1, B1=665000, B2=12635000)

93.410 bits.

[QUOTE=Miszka;443930]It's my the best result[/QUOTE]

Congrats!
An awesome finding.

[QUOTE=lycorn;444130]Congrats!
An awesome finding.[/QUOTE]
Many thanks for you.
My previous the best result was 24523881623890845010007531389564120430998338703 (154,1 bits 47 digits) for [url=http://www.mersenne.org/report_exponent/?exp_lo=31051&exp_hi=&full=1] M31051[/url]

Just out of curiosity, what were the bounds used? It's funny that they do not show up in the report.

[QUOTE=lycorn;444168]Just out of curiosity, what were the bounds used? It's funny that they do not show up in the report.[/QUOTE]

ECM found a factor in curve #24, stage #2
Sigma=3677350809829694, B1=3000000, B2=300000000.
UID: mikr/MSI, M31051 has a factor: 24523881623890845010007531389564120430998338703, AID: 37DA0E9F3CF2495E43A0992C161441C5

[QUOTE=Miszka;444183]ECM found a factor in curve #24, stage #2
Sigma=3677350809829694, B1=3000000, B2=300000000.
UID: mikr/MSI, M31051 has a factor: 24523881623890845010007531389564120430998338703, AID: 37DA0E9F3CF2495E43A0992C161441C5[/QUOTe]
It was previously reported by mikr in 2014
[url]http://www.mersenne.org/report_exponent/?exp_lo=31051&exp_hi=&full=1&ecmhist=1[/url]

Isn't that what [i]Miszka[/i] just said?

[QUOTE=James Heinrich;444187]Isn't that what [i]Miszka[/i] just said?[/QUOTE]:redface:
oops, I thought that was a report of a new factor.

[QUOTE=Uncwilly;444186]It was previously reported by mikr in 2014
[url]http://www.mersenne.org/report_exponent/?exp_lo=31051&exp_hi=&full=1&ecmhist=1[/url][/QUOTE]

Right. But you won't find there the usual info about the bounds. That's why I asked.
It's not common to find a 47-digit factor with a 3e6 B1!

I found very rough prime factor of [URL="http://www.mersenne.org/report_exponent/?exp_lo=199453&exp_hi=&full=1&ecmhist=1"]M199453[/URL]: 703714563044693056037968277785991 (109.1 bits)
k (90.511 bits) = 5 × 352822250377127973025208083
(ECM curve 219, stage #1, B1=250000, B2=25000000)

[QUOTE=Miszka;444519]I found very rough prime factor of [URL="http://www.mersenne.org/report_exponent/?exp_lo=199453&exp_hi=&full=1&ecmhist=1"]M199453[/URL]: 703714563044693056037968277785991 (109.1 bits)
k (90.511 bits) = 5 × 352822250377127973025208083
(ECM curve 219, stage #1, B1=250000, B2=25000000)[/QUOTE]

Hah, I can top that:

[URL="http://www.mersenne.org/report_exponent/?exp_lo=5501&full=1"]M5501[/URL], factor 124424631532117825221239927348589023

k = 11309273907663863408583887234011 (a 32-digit prime)

[QUOTE=GP2;444523]Hah, I can top that:

[URL="http://www.mersenne.org/report_exponent/?exp_lo=5501&full=1"]M5501[/URL], factor 124424631532117825221239927348589023

k = 11309273907663863408583887234011 (a 32-digit prime)[/QUOTE]

The result is wonderful. A little bit of its value decreases, that this is't ... the first factor :smile:

[QUOTE=GP2;444523]Hah, I can top that[/QUOTE]By peeking in the database I can top that too :wink:

Actually the way the factored k values are stores are not easily searchable to find the largest component, but by looking at exponents with k longer than 100 digits I believe the two winners are:

132-digit: [url=http://www.mersenne.ca/M1129]M1129[/url] = 5 * 349 * 680893544214512409631723241923984408474147200813444413919110673154410812361054312317836168473471660651160327499621967599043897690871

128-digit: [url=http://www.mersenne.ca/M1109]M1109[/url] = 377609968577357 * 29390896242584729489297434180738860022421056237104270110730836700511316902860789212658605173244533094779061821974098972841052043

P-1 found a factor in stage #1, B1=2700000.
UID: mikr/MSI, M2748857 has a factor: 2283574827904867564040066470770610598552767 (P-1, B1=2700000)
43 digits 140.712 bits
This is my new high score record found by P-1

[QUOTE=Miszka;448259]
43 digits 140.712 bits
This is my new high score record found by P-1[/QUOTE]

One-upmanship:

[URL="http://www.mersenne.ca/exponent/2797"]M2797[/URL]:
99966410000212091183671262757251795787241105921
47 digits 156.130 bits
Was found with P−1 stage 1, B1=100,000,000,000

( k = 2[SUP]8[/SUP] × 3[SUP]3[/SUP] × 5 × 13 × 89 × 12503047 × 306137893 × 1814314547 × 64354512667 )

P-1 found a factor in stage #2, B1=670000, B2=12730000.
UID: Jwb52z/Clay, M80126297 has a factor: 11647669222017335700785687 (P-1, B1=670000, B2=12730000),

83.268 bits.

P-1 found a factor in stage #2, B1=670000, B2=12730000.
UID: Jwb52z/Clay, M80254519 has a factor: 2066533873402962369354743 (P-1, B1=670000, B2=12730000).

80.773 bits.

P-1 found a factor in stage #1, B1=675000.
UID: Jwb52z/Clay, M80582011 has a factor: 6767080053629333125464247 (P-1, B1=675000)

82.485 bits.

P-1 found a factor in stage #1, B1=675000.
UID: Jwb52z/Clay, M80672513 has a factor: 7720342787621215578700001 (P-1, B1=675000)

82.675 bits.

[url=http://mersenne.ca/M78044321]M78044321[/url] has a factor: 136965029078438306789901990063200306098597292653297 (P-1, B1=655000, B2=13100000, E=12)

Composite (77+90 bits) of course, but this is a P-1 re-run (previously ran with stage1 only that missed both factors).

Congrats, James.

On this side of the pond, I have no specific factor to report, but I just reported in a streak of 11 successes in 159 TF-73 attempts on consecutive candidates from 90505267 to 90512179.

That's a 1 in 14.45 success ratio, or roughly five times as high as you'd expect, on average.

I'd call that noteworthy. Nontheless, I'll spare you the smallish factors. :yawn:

[URL="http://mersenne.org/M80910023"]M80910023[/URL] has a factor: 8761542675966749331731213096500505849 (P-1, B1=680000, B2=13600000, E=6)
122.72 bits

A factor was found today (not by me) for the previously unfactored [M]M11027[/M]. Congratulations.

Right. A great shot. Was it Sid or Andy? ;)

[QUOTE=GP2;456811]A factor was found today (not by me) for the previously unfactored [M]M11027[/M]. Congratulations.[/QUOTE]

S&A broadcast an ambition to find something like this back earlier in the year!
Likely, mission accomplished.

[QUOTE=snme2pm1;456828]S&A broadcast an ambition to find something like this back earlier in the year!
Likely, mission accomplished.[/QUOTE]

Tis I ...Tis I :fusion:

Etch 11027 F-ECM 2017-04-15 18:04 288363872191768892050551279270150054945736765655279

Mission Phase I. I'd like to find 2 more. :fingerscrossed:

[QUOTE=petrw1;456839]Tis I ...Tis I :fusion:

Etch 11027 F-ECM 2017-04-15 18:04 288363872191768892050551279270150054945736765655279

Mission Phase I. I'd like to find 2 more. :fingerscrossed:[/QUOTE]

Nice find!

Back to 4007....

[QUOTE=petrw1;456839]Tis I ...Tis I :fusion:

Etch 11027 F-ECM 2017-04-15 18:04 288363872191768892050551279270150054945736765655279
[/QUOTE]

Congratulations again.

I think you're also working on Fermat number F12 (2[SUP]4096[/SUP]+1) ?

You should specify the already-known factors in the worktodo line, otherwise you will keep rediscovering them and reporting them to PrimeNet.

[CODE]
ECM2=1,2,4096,1,800000000,80000000000,1,"114689,26017793,63766529,190274191361,1256132134125569,568630647535356955169033410940867804839360742060818433"
[/CODE]

[QUOTE=GP2;456923]Congratulations again.

I think you're also working on Fermat number F12 (2[SUP]4096[/SUP]+1) ?

You should specify the already-known factors in the worktodo line, otherwise you will keep rediscovering them and reporting them to PrimeNet.

[CODE]
ECM2=1,2,4096,1,800000000,80000000000,1,"114689,26017793,63766529,190274191361,1256132134125569,568630647535356955169033410940867804839360742060818433"
[/CODE][/QUOTE]

I was assuming (seems incorrectly) that PrimeNet would do that for me.
I simply ask for ECM-FERMAT assignments and it give me 4096 for example with a line like this...only specifying 1 known factor.

ECM2=<id>,1,2,4096,1,800000000,80000000000,3,"1256132134125569"

[QUOTE=petrw1;457010]I was assuming (seems incorrectly) that PrimeNet would do that for me.
I simply ask for ECM-FERMAT assignments and it give me 4096 for example with a line like this...only specifying 1 known factor.

ECM2=<id>,1,2,4096,1,800000000,80000000000,3,"1256132134125569"[/QUOTE]

That would be a bug. The relevant lines for Fermat numbers, assuming 3 curves, should be:

[CODE]
ECM2=1,2,4096,1,800000000,80000000000,3,"114689,26017793,63766529,190274191361,1256132134125569,568630647535356955169033410940867804839360742060818433"
ECM2=1,2,8192,1,260000000,26000000000,3,"2710954639361,2663848877152141313,3603109844542291969,319546020820551643220672513"
ECM2=1,2,16384,1,260000000,26000000000,3,"116928085873074369829035993834596371340386703423373313"
ECM2=1,2,32768,1,110000000,11000000000,3,"1214251009,2327042503868417,168768817029516972383024127016961"
ECM2=1,2,65536,1,110000000,11000000000,3,"825753601,188981757975021318420037633"
ECM2=1,2,131072,1,110000000,11000000000,3,"31065037602817,7751061099802522589358967058392886922693580423169"
ECM2=1,2,262144,1,44000000,4400000000,3,"13631489,81274690703860512587777"
ECM2=1,2,524288,1,44000000,4400000000,3,"70525124609,646730219521,37590055514133754286524446080499713"
ECM2=1,2,1048576,1,44000000,4400000000,3
ECM2=1,2,2097152,1,11000000,1100000000,3,"4485296422913"
ECM2=1,2,4194304,1,11000000,1100000000,3,"64658705994591851009055774868504577"
ECM2=1,2,8388608,1,3000000,300000000,3,"167772161"
ECM2=1,2,16777216,1,3000000,300000000,3
ECM2=1,2,33554432,1,1000000,100000000,3,"25991531462657,204393464266227713,2170072644496392193"
ECM2=1,2,67108864,1,250000,25000000,3,"76861124116481"
ECM2=1,2,134217728,1,250000,25000000,3,"151413703311361,231292694251438081"
ECM2=1,2,268435456,1,250000,25000000,3,"1766730974551267606529"
ECM2=1,2,536870912,1,50000,5000000,3,"2405286912458753"
[/CODE]

It's a problem, because ECM testing by default stops as soon as any factor is found. So if it keeps finding existing factors, the effort is more or less wasted.

Wouldn't it be much more efficient to run ECM work on the 1187 digit composite rather than the original number?

P-1 for P.I.E.S. (PhiExtensions=1; KeepPminus1SaveFiles=0)
 

[CODE]30434^2097152-30434^1048576+1 has a factor: 40099774805853786341377 (P-1, B1=7500, B2=100000)[/CODE]
... ergo: P-1 is not useless for P.I.E.S.

[QUOTE=Batalov;457435][CODE]30434^2097152-30434^1048576+1 has a factor: 40099774805853786341377 (P-1, B1=7500, B2=100000)[/CODE]
... ergo: P-1 is not useless for P.I.E.S.[/QUOTE]

[CODE]? allocatemem(1000000000)
*** Warning: new stack size = 1000000000 (953.674 Mbytes).
? #digits(30434^2097152-30434^1048576+1)
9402286
[/CODE]

:omg:

You got that right ;-)

[QUOTE=Batalov;457449]You got that right ;-)[/QUOTE]
Which right? Why he has some rights which I don't have? Is this constitutional? :shock:

[QUOTE=Xyzzy;457034]Wouldn't it be much more efficient to run ECM work on the 1187 digit composite rather than the original number?[/QUOTE]

Actually, it's only a 1133-digit cofactor, you're forgetting the 54-digit largest factor 568630647535356955169033410940867804839360742060818433

And not "much" more efficient, since F12 itself is 1234 digits long.

In any case, if you supply the list of known factors in double quotes at the end of the ECM2= line, then mprime has all the information it needs and presumably does its work in the most efficient way possible. I don't know if the algorithm works faster on the original number or the cofactor.

Today someone discovered a new 44-digit factor of [M]M2957[/M], the third-known factor of that exponent. The cofactor is composite, according to factordb

[QUOTE=GP2;457464]Actually, it's only a 1133-digit cofactor, you're forgetting the 54-digit largest factor 568630647535356955169033410940867804839360742060818433[/QUOTE]It would be difficult for us to [URL="http://caramel.loria.fr/f12.txt"]forget that factor[/URL].

Our error is typing too fast and thinking too little.

[QUOTE=GP2;457464]And not "much" more efficient, since F12 itself is 1234 digits long.[/QUOTE]F12 is 101 times bigger than the C1133. That seems like a big difference, but we are willing to be educated!

:mike:

[QUOTE=Xyzzy;457481]
F12 is 101 times bigger than the C1133. That seems like a big difference, but we are willing to be educated![/QUOTE]

Are you sure?

F13 is roughly F12 times bigger than F12... no wonder it's taking so long to find more Fermat factors.:confused:

[QUOTE=Xyzzy;457481]It would be difficult for us to [URL="http://caramel.loria.fr/f12.txt"]forget that factor[/URL].
[/QUOTE]
That was my thinking too, haha.... but you were faster to post it.

[QUOTE=GP2;457488]Are you sure?

F13 is roughly F12 times bigger than F12... no wonder it's taking so long to find more Fermat factors.:confused:[/QUOTE]

He wanna say "digits" not "times". Typo.

P-1 found a factor in stage #2, B1=675000, B2=12825000.
UID: Jwb52z/Clay, M81180581 has a factor: 97246609841457762906841 (P-1, B1=675000, B2=12825000)

76.364 bits.

P-1 found a factor in stage #1, B1=680000.
UID: Jwb52z/Clay, M81309119 has a factor: 212788775459776906189271 (P-1, B1=680000)

77.494 bits.

P-1 found a factor in stage #1, B1=680000.
UID: Jwb52z/Clay, M81282431 has a factor: 465065881821653916530959 (P-1, B1=680000),

78.622 bits.

My second sub 20000 ECM Factor of 2017
 

Hand_In_The_Box 14173 F-ECM 2017-06-06 22:21 63.2 5451595560230412055196637501309406085341593764073929 6.5642

Almost 172 bits!!!

[QUOTE=petrw1;460690]Hand_In_The_Box 14173 F-ECM 2017-06-06 22:21 63.2 5451595560230412055196637501309406085341593764073929 6.5642

Almost 172 bits!!![/QUOTE]

Congratulations! What bounds were you running? All P95, or GMP-ECM hybrid?

[QUOTE=VBCurtis;460693]Congratulations! What bounds were you running? All P95, or GMP-ECM hybrid?[/QUOTE]

Thx
Just prime95 to the prescribed bounds.

Great find!
More to come. It´s not yet mid year...:smile:

Not a Mersenne, but a [URL="http://factordb.com/index.php?query=L(59863)"]Lucas factor[/URL], humorously large:

[CODE]Input number is 6569290416...8007744099 (12498 digits)
Using B1=100000, B2=39772318, polynomial x^1, x0=2094478791
Step 1 took 30599ms
Step 2 took 31517ms
********** Factor found in step 2: 52215613273214538217140880496129
Found prime factor of 32 digits: 52215613273214538217140880496129
Composite cofactor [/CODE]

P-1 found a factor in stage #1, B1=685000.
UID: Jwb52z/Clay, M82286773 has a factor: 63196368814656374199671 (P-1, B1=685000)

75.742 bits.

P-1 found a factor in stage #2, B1=685000, B2=13015000.
UID: Jwb52z/Clay, M82336229 has a factor: 32884975554466910081290869271 (P-1, B1=685000, B2=13015000),

94,731 bits.

[QUOTE=Jwb52z;463566]P-1 found a factor in stage #2, B1=685000, B2=13015000.
UID: Jwb52z/Clay, M82336229 has a factor: 32884975554466910081290869271 (P-1, B1=685000, B2=13015000),

94,731 bits.[/QUOTE]

Wow, 94 thousand bits, must be a record!

[QUOTE=Gordon;463614]Wow, 94 thousand bits, must be a record![/QUOTE]Welcome to planet Earth where not everyone follows the same digit grouping conventions.

.

"." means a moderation issue, at least when it comes to Seti@home.

Except for that, I am not supposed to be here either.

[QUOTE=retina;463617]Welcome to planet Earth where not everyone follows the same digit grouping conventions.[/QUOTE]

Just to put on the table...

It can sometimes be amusing to push the envelope, and see what happens.

P-1 found a factor in stage #2, B1=695000, B2=13205000.
UID: Jwb52z/Clay, M82642103 has a factor: 3695652401483277360772926673 (P-1, B1=695000, B2=13205000),

91.578 bits.

It was a typo, actually, in my case, but I do know that Europeans don't use commas and periods the way Americans do. I haven't done that before by mistake.

P-1 found a factor in stage #2, B1=665000, B2=12136250.
UID: Jwb52z/Clay, M83404637 has a factor: 5589507944734239641155009 (P-1, B1=665000, B2=12136250)

82.209 bits.

I pilfered a factor from FactorDB.

M[M]1489[/M] has a factor: 95909518295775374166321292697000685895150503357477127

(53 digits)

It was [URL="http://factordb.com/index.php?id=1100000000956003192"]reported (by who?) to FactorDB on August 17[/URL]. The remaining 295-digit cofactor is composite.

Note that a 68-digit factor of M[M]1471[/M] was reported to FactorDB on August 31, and this was [URL="http://mersenneforum.org/showthread.php?t=19407&p=466979"]spotted by axn a few days later[/URL]. M1471 is now fully factored.

I ran a systematic check via a screenscraping script just now, comparing all factors for exponents below 10,000 and found this new factor.

Someone out there is finding large new factors for very small Mersenne exponents, independently of GIMPS. I guess it's worthwhile to rerun the script every few weeks or so, going forward.

Just a month ago, I ran a systematic crosscheck of exponents under 1 million (prompted by [URL="http://mersenneforum.org/showthread.php?t=22501"]this thread[/URL]), and synchronized the data on both FactorDB and GIMPS. Obviously, the new factors for M1471 and M1489 were reported to FactorDB more recently than this.

P-1 found a factor in stage #2, B1=665000, B2=12136250.
UID: Jwb52z/Clay, M83218433 has a factor: 11731332775665701203434915133649 (P-1, B1=665000, B2=12136250)

103.210 bits.

P-1 found a factor in stage #2, B1=665000, B2=12136250.
UID: Jwb52z/Clay, M83536261 has a factor: 7490746336097080588566003191 (P-1, B1=665000, B2=12136250)

92.597 bits.

P-1 found a factor in stage #2, B1=670000, B2=12562500.
UID: storm5510/7700_Kaby_Lake, M84195253 has a factor: 2369133135664536495703801369 (P-1, B1=670000, B2=12562500)

90.936 bits.

P-1 found a factor in stage #2, B1=670000, B2=12562500.
UID: storm5510/7700_Kaby_Lake, M84215177 has a factor: 46028976926137780014126464377 (P-1, B1=670000, B2=12562500)

95.217 bits.

This is the second one in as many days.

P-1 found a factor in stage #2, B1=670000, B2=12395000.
UID: Jwb52z/Clay, M84557219 has a factor: 98272228738510755321309371330593 (P-1, B1=670000, B2=12395000)

106.277 bits.

Over 138 Bits
 

2307677
F-PM1
2017-12-06 02:44
Factor: 305924195866403106191552498276182730434001 / (P-1, B1=6000000, B2=180000000, E=12)

[QUOTE=petrw1;473230]2307677
F-PM1
2017-12-06 02:44
Factor: 305924195866403106191552498276182730434001 / (P-1, B1=6000000, B2=180000000, E=12)[/QUOTE]
k=66284015455023191328672188152021000=2^3 × 5^3 × 7 × 3433 × 15581 × 36269 × 249647 × 507697 × 38510141

42 digits, 138 bits, nice find!

P-1 found a factor in stage #1, B1=670000.
UID: Jwb52z/Clay, M84928609 has a factor: 280163322369309428227183 (P-1, B1=670000)

77.891 bits.

[QUOTE=petrw1;473230]2307677
F-PM1
2017-12-06 02:44
Factor: 305924195866403106191552498276182730434001 / (P-1, B1=6000000, B2=180000000, [COLOR=DarkRed][B]E=12[/B][/COLOR])[/QUOTE]

What is the significance of the item in bold above? I've seen this in some of my PM1 tests, but usually much lower.

[QUOTE=storm5510;473772]What is the significance of the item in bold above? I've seen this in some of my PM1 tests, but usually much lower.[/QUOTE][url=http://www.mersennewiki.org/index.php/Brent-Suyama_extension]Brent-Suyama extension[/url] - It potentially allows finding some types of factors outside the expected B1/B2 bounds for P-1, but requires generous amounts of RAM. Values can be up to 12 if lots of RAM available, 6 if less RAM available (and I think sometimes it could be 3(?) but don't quote me on that).
To get E=12 on current ~80M range exponents you'll need something in the order of ~10GB allocated to P-1.

ECM found a factor in curve #3, stage #2

Sigma=6233548487723791, B1=50000, B2=5000000.

UID: nitro/haswell, M2004917 has a factor: 308301002035645140354241

**

78.03 bits

150 bits
 

ECM found a factor in curve #1, stage #2
Sigma=3200091177920085, B1=50000, B2=5000000.
UID: nitro/haswell, M2122937 has a factor: 1498439627815726005558688529761315320138259649 (ECM curve 1, B1=50000, B2=5000000), AID: EDB1D4AB43C885B359204C31FB202EAA


...a quick check at mersenne.ca shows this is actually a composite factor...

P-1 found a factor in stage #1, B1=675000.
UID: Jwb52z/Clay, M85393921 has a factor: 14072321778883706915013177017 (P-1, B1=675000)

93.507 bits

P-1 found a factor in stage #2, B1=675000, B2=12487500.
UID: Jwb52z/Clay, M85629839 has a factor: 816642824855310862859977 (P-1, B1=675000, B2=12487500),

79.434 bits.

P-1 found a factor in stage #1, B1=675000.
UID: Jwb52z/Clay, M85654649 has a factor: 402442961353006714077071 (P-1, B1=675000)

78.413 bits

P-1 found a factor in stage #2, B1=675000, B2=12487500.
UID: Jwb52z/Clay, M85758499 has a factor: 200074641364733559033419273 (P-1, B1=675000, B2=12487500)

87.371 bits.

This one is smooth! [URL="http://www.mersenne.org/report_exponent/?exp_lo=24639113&full=1"]M24639113[/URL] has a factor: [URL="http://www.mersenne.ca/factor/1542983967870622198424294628794130841"]1542983967870622198424294628794130841[/URL].
P-1, B1 = 500,000, B2 = 30,000,000, E = 12.
37 digits, 120.215 bits.
[$$]k=2^2 \cdot 3 \cdot 5 \cdot 29 \cdot 61 \cdot 313 \cdot 509 \cdot 5879 \cdot 8221 \cdot 9133 \cdot 4194919[/$$]

[URL="http://www.mersenne.org/M15773"]M15773[/URL] has a factor: [URL="http://www.mersenne.ca/factor/17579521249732269431622694421369772823"]17579521249732269431622694421369772823[/URL].
38 digits, 123.725 bits.
Found in stage 2 of ECM with B1 = 1,000,000 and B2 = 100,000,000.
[$]k = 3^2 \cdot 1508475559895261 \cdot 41047050622854043[/$]

[QUOTE=kruoli;479327][URL="http://www.mersenne.org/M15773"]M15773[/URL] has a factor: [URL="http://www.mersenne.ca/factor/17579521249732269431622694421369772823"]17579521249732269431622694421369772823[/URL].
38 digits, 123.725 bits.
Found in stage 2 of ECM with B1 = 1,000,000 and B2 = 100,000,000.
[$]k = 3^2 \cdot 1508475559895261 \cdot 41047050622854043[/$][/QUOTE]

Can you check your logs for the sigma for that particular ECM curve? That will tell us the group order (the generalized analog to k in P-1 method, the part that needs to be smoother than the bounds).

Sure! Here it is: [$]\sigma = 831178265486145[/$]. If I'm not mistaken, group order is [$$]17579521249732269439175142576334117224 = 2^3 \cdot 3^4 \cdot 61^2 \cdot 71 \cdot 137 \cdot 173 \cdot 883 \cdot 9209 \cdot 44909 \cdot 414559 \cdot 28618999[/$$]

Is recording the sigma useful in general? Primenet doesn't store it. Should it?

FactorDB lets you report it. Is it worth going through old results.txt files and reporting B1, B2, sigma for factors of a certain size for sufficiently small exponents?

For example, back in October and November 2016 I found

M5479 has a factor: 13557556381615196797243034050392909446329
Sigma=7054537469636144, B1=3000000, B2=300000000
order = 13557556381615196797212833579170371231744 = 2^13 · 3^2 · 7 · 71 · 29587 · 48859 · 126457 · 742673 · 787907 · 3458849

M5849 has a factor: 6122074172317059755884428199928856623
Sigma=3773616030419932, B1=3000000, B2=300000000
order = 6122074172317059756386103969515680128 = 2^7 · 3 · 17 · 271^2 · 653 · 626117 · 1229269 · 2347777 · 10821997

M6317 has a factor: 4012681826290985504902063790032196593
Sigma=7077307037954735, B1=3000000, B2=300000000
order = 4012681826290985506009411978310188020 = 2^2 · 3^2 · 5 · 251 · 12541 · 77747 · 302663 · 389651 · 787601 · 980689

I reported the sigmas to FactorDB just now.

There are various others. What are the criteria for noteworthiness?

Two interesting P-1 finds today, both exponents had 200+ ECM curves with B1=50,000 and previous P-1 (B1=2e6 B2=20e6 E=12)

Found with B1=10e6 , B2 =200e6 E=12)

[URL]http://www.mersenne.ca/exponent/1618957[/URL]
33digits, 109bits
k=193635371239965998637830543 = 7 × 29 × 761 × 1129 × 58787 × 130729 × 144463063

[URL]http://www.mersenne.ca/exponent/1619249[/URL]
25digits, 81bits
k=597596506944850360 = 23 × 5 × 7727 × 81043 × 23857319

[QUOTE=VictordeHolland;479457]
k=597596506944850360 =23 × 5 × 7727 × 81043 × 23857319[/QUOTE]
Copy past mistake, it should be:
2[B]^3[/B] × 5 × 7727 × 81043 × 23857319

P-1 found a factor in stage #1, B1=675000.
UID: Jwb52z/Clay, M85843097 has a factor: 1359449597493721279537921 (P-1, B1=675000)

80.169 bits.

Hi,

not a big factor... but a smooth one:
P-1 found a factor in stage #1, B1=695,000.
M85,872,673 has a factor: 132,249,907,283,167,396,650,217 (76.80 Bits; k = 770,034,882,244,596 = 2[SUP]2[/SUP] * 3 * 19[SUP]2[/SUP] * 31 * 101 * 157 * 431 * 839)

Oliver

Yay, four 100bits+ factors in a couple of days

[code]
ECM found a factor in curve #26, stage #2
Sigma=6601270117148099, B1=50000, B2=5000000.
M1645829 has a factor: 4926163898475197542012571417906273 (ECM curve 26, B1=50000, B2=5000000)[/code]k = 1496560061365791203707241584 = 2^4 × 366327723677 × 255331490875187
34 digits (112 bits)
Lucky to find it with those bounds and only after 26 curves :)

[code]
ECM found a factor in curve #189, stage #1
Sigma=8480282508537123, B1=50000, B2=5000000.
M1646017 has a factor: 1508150793506270218417297 (ECM curve 189, B1=50000, B2=5000000)[/code]k = 671925754144305528132925 = 5^2 × 11 × 2262149 × 1080108506869603
31 digits (101 bits)
Pretty nice also

[code]
P-1 found a factor in stage #2, B1=10000000, B2=200000000, E=12.
M1635061 has a factor: 35277055408841049507268416482009 (P-1, B1=10000000, B2=200000000, E=12)[/code]k = 10787687862667218381231164 = 2^2 × 7 × 67 × 337 × 102107 × 3815521 × 43798201
32 digits (105 bits)

[code]
P-1 found a factor in stage #2, B1=10000000, B2=200000000, E=12.
M1632031 has a factor: 5765639839704486562062940217495923385660941630658516500657 (P-1, B1=10000000, B2=200000000, E=12)[/code]Too bad it is composite:
3653580423682983757805163337 and 1578079355344379124902894328361
but still 28 digits (92 bits) and 31 digits (101 bits)

Victor out.

89 bits & 75 bits
 

ECM found a factor in curve #2, stage #2
Sigma=4638489409098898, B1=50000, B2=5000000.
UID: nitro/haswell, M2363233 has a factor: 653802529177774532317345711 (ECM curve 2, B1=50000, B2=5000000), AID: AAD7ED003888C5890508D85DF6B13096

ECM found a factor in curve #1, stage #2
Sigma=4290627876618080, B1=50000, B2=5000000.
UID: nitro/haswell, M2350331 has a factor: 62772178479336230190607 (ECM curve 1, B1=50000, B2=5000000), AID: 02EDEEAFE3CDC8C4486449D27CFCA701

Exponent and factor both end in 6 and 3
 

56663333 Factored 117668043758277867795710633

Of the ~124 million known factors, only 10 of them match the pattern of multiple 6 plus multiple 3 ending for both exponent and factor (yours has many in the exponent but only a single 6 at the end of the factor. And only one of them is in GIMPS range:[code] M287956633 has a factor: 188288997950876633
M1267676633 has a factor: 1508159960986633
M1394486633 has a factor: 8003940505376633
M1614086633 has a factor: 266921028729566633
M2599036633 has a factor: 77201784146633
M3149666633 has a factor: 45763723876166633
M3686626633 has a factor: 3206273929226633
M3863026633 has a factor: 81817760631056633
M4088396633 has a factor: 4589101358478106633
M4246166633 has a factor: 168589799996633[/code]If you cared to know :mooc:

[B][/B][QUOTE=petrw1;479978]56663333 Factored 117668043758277867795710633[/QUOTE]

Similarly:
54297751 Factored 413618853521086092885751

There are 27 factors that match the last 7 digits of the exponent and factor, and none that match more than that:[code]M29999999 has a factor: 59999999
M32548409 has a factor: 68596162548409
M304382063 has a factor: 89449974382063
M389999999 has a factor: 779999999
M517868633 has a factor: 1164015397868633
M892082951 has a factor: 4861852082951
M1229999999 has a factor: 2459999999
M1236290281 has a factor: 4796806290281
M1254617737 has a factor: 411514617737
M1340466791 has a factor: 6020961280466791
M1426591919 has a factor: 5601259236591919
M1454117647 has a factor: 26174117647
M1496367713 has a factor: 335186367713
M1908028169 has a factor: 137378028169
M1960041841 has a factor: 470410041841
M2044060871 has a factor: 68469845674060871
M2233922231 has a factor: 460925173922231
M2291942959 has a factor: 1288071942959
M2853650119 has a factor: 16986415113650119
M3001111111 has a factor: 30011111111
M3065961401 has a factor: 4292345961401
M3287142857 has a factor: 26297142857
M3346923431 has a factor: 16251087126923431
M3420891679 has a factor: 21572423440891679
M3474253703 has a factor: 9151184253703
M3496569617 has a factor: 993193606569617
M3863902439 has a factor: 162283902439[/code]

I got bored and decided to rerun P-1 on exponents with only stage 1 done:

[QUOTE][Sun Feb 18 10:47:26 2018]
P-1 found a factor in stage #2, B1=800000, B2=12500000, E=12.
UID: ixfd64/dchia-pro, M47501749 has a factor: 793528449260403299636240009 (P-1, B1=800000, B2=12500000, E=12)[/QUOTE]

I'm glad the effort turned out to be worthwhile!

Nothing spectacular, but a nice result.

[url]http://www.mersenne.ca/exponent/52660711[/url]

52660711 has a factor 90657772754508534123079
76.3 bits, found via P-1 (stage 2?)
This was marked as poorly P-1'ed before by Mersenne.ca. (b1=855,000,b2=)

I spent 1.1 GHz/days. 1 bad LL and 2 more spent 100 GHz/days [B][U]each[/U][/B]. The bad LL was done by the user that did the initial P-1 back in 2011. And over 33 GHz/days of additional T-F was done after the initial P-1.

:picard:

[QUOTE=ixfd64;480383]I got bored and decided to rerun P-1 on exponents with only stage 1 done:



I'm glad the effort turned out to be worthwhile![/QUOTE]

I'm doing lots of these in the 50-59M range.

[QUOTE=GP2;479455]What are the criteria for noteworthiness?[/QUOTE]

Finding the first factor of a Mersenne number is the general man's successs (German: "der Erfolg des kleinen/gemeinen Mannes", maybe knows how to translate this a bit better). So I wouldn't put too many restrictions on that. While I feel that every factor about 100 bit is somewhat noteworthy, that doesn't mean everybody should post those factors, and it doesn't mean that this is a requirement, either.