Gratuitous factors thread - Page 42

Nooks · 2018-08-17, 13:19

ECM on a C213, the last divisor of (34*10^229-61)/9 with sigma=1:3941682105:

Using B1=2900000000, B2=82640965106716, polynomial Dickson(30), sigma=1:3941682105
[...]
********** Factor found in step 2: 35020442769329876367522852735060830348867981850170604303099578467
Found prime factor of 65 digits: 35020442769329876367522852735060830348867981850170604303099578467
Prime cofactor 6463948784722816185901384621852688761921664616020783901443547268726228461664676485561963639543974467240297445194995726733180417921657435498535243769 has 148 digits

The factor was found on the 25th curve; taking into account all the other cores running curves this was the 2400th curve of only 9600 I planned to run before handing the problem to CADO-NFS, so I'm counting myself quite lucky!

ET_ · 2018-08-17, 13:49

Quote:

Originally Posted by Nooks

ECM on a C213, the last divisor of (34*10^229-61)/9 with sigma=1:3941682105:

Using B1=2900000000, B2=82640965106716, polynomial Dickson(30), sigma=1:3941682105
[...]
********** Factor found in step 2: 35020442769329876367522852735060830348867981850170604303099578467
Found prime factor of 65 digits: 35020442769329876367522852735060830348867981850170604303099578467
Prime cofactor 6463948784722816185901384621852688761921664616020783901443547268726228461664676485561963639543974467240297445194995726733180417921657435498535243769 has 148 digits

The factor was found on the 25th curve; taking into account all the other cores running curves this was the 2400th curve of only 9600 I planned to run before handing the problem to CADO-NFS, so I'm counting myself quite lucky!

wpolly · 2018-08-18, 19:49

Code:

Input number is (109^123-1)/(109^41-1)/95898591887152691733740679 (142 digits)
Using B1=43000000, B2=240490660426, polynomial Dickson(12), sigma=1:3742107819
Step 1 took 66545ms
Step 2 took 23004ms
********** Factor found in step 2: 113910660004153337924628664386678247208828533
Found prime factor of 45 digits: 113910660004153337924628664386678247208828533
Prime cofactor ((109^123-1)/(109^41-1)/95898591887152691733740679)/113910660004153337924628664386678247208828533 has 98 digits

This factor appeared on curve 92 out of a planned 4000.

BudgieJane · 2018-09-16, 17:54

C135 from 1208^47+1:

Code:

prp43 = 7872050983542095687417246190511880248639711
prp92 = 16940363046999582482928413622346911064605327855533940683539949731286830685125532654826597073

C125 from 1259^47+1

Code:

prp38 = 98345853344307565253324824092518095601
prp87 = 929528781257601652853545435226628885326214271769204819819291780270828421426874911996487

fivemack · 2018-12-10, 13:54

199-digit GNFS, done entirely locally

Code:

N 1253697014483921701519774710080293856978446067093422585355224278757029355514329819946916985971979863264272814638205843444068083099253312799641803553719988196912895006268194994880801257942554688556001
SKEW 127028183.52
A0 -595638964036345481237071140491743854143245809544
A1 29926818433789606747718647951662435504208
A2 307924512754708078991927303315680
A3 -4781679268252586458599169
A4 -22400530233973836
A5 102927636
R0 -104023657306189391164144906961130612015
R1 651664577069232468431

Sieved Q=30M .. 285M and 330M..335M with gnfs-lasieve4I16e; 12 Aug - 10 Nov on 64 cores E5-2650 and some other resources; linear algebra was 27 days on 14 cores i9-7940X

Code:

lpbr: 33
lpba: 33
mfbr: 66
mfba: 96
alambda: 3.5
rlambda: 2.4
alim: 268000000
rlim: 268000000

Code:

Tue Nov 13 07:30:38 2018  matrix is 48788680 x 48788857 (23378.5 MB) with weight 7047295017 (144.44/col)
Tue Nov 13 07:30:38 2018  sparse part has weight 5543070617 (113.61/col)
Tue Nov 13 07:40:47 2018  filtering completed in 2 passes
Tue Nov 13 07:40:57 2018  matrix is 48786801 x 48786976 (23378.4 MB) with weight 7047214552 (144.45/col)
Tue Nov 13 07:40:57 2018  sparse part has weight 5543053801 (113.62/col)
Tue Nov 13 07:43:08 2018  matrix starts at (0, 0)
Tue Nov 13 07:43:15 2018  matrix is 48786801 x 48786976 (23378.4 MB) with weight 7047214552 (144.45/col)
Tue Nov 13 07:43:15 2018  sparse part has weight 5543053801 (113.62/col)
Tue Nov 13 07:43:15 2018  saving the first 240 matrix rows for later
Tue Nov 13 07:43:27 2018  matrix includes 256 packed rows
Tue Nov 13 07:43:42 2018  matrix is 48786561 x 48786976 (21440.4 MB) with weight 5118664178 (104.92/col)
Tue Nov 13 07:43:42 2018  sparse part has weight 4839889639 (99.20/col)
Tue Nov 13 07:43:42 2018  using block size 8192 and superblock size 473088 for processor cache size 19712 kB
Tue Nov 13 07:45:56 2018  commencing Lanczos iteration (14 threads)
Tue Nov 13 07:45:56 2018  memory use: 29766.8 MB
Tue Nov 13 07:47:23 2018  linear algebra at 0.0%, ETA 637h43m
Tue Nov 13 07:47:47 2018  checkpointing every 80000 dimensions
Mon Dec 10 04:01:57 2018  lanczos halted after 191142 iterations (dim = 48786558)
Mon Dec 10 04:05:48 2018  recovered 29 nontrivial dependencies
Mon Dec 10 04:06:03 2018  BLanczosTime: 2324842
Mon Dec 10 04:06:03 2018  elapsed time 645:47:23

Code:

Mon Dec 10 12:47:23 2018  p82 factor: 9214409416745614101198894993721726856303159042273240016125104117470329343249250561
Mon Dec 10 12:47:23 2018  p117 factor: 136058314513954814229280792975681347764936790375643059794253062274788902853667069820292458749493930656793985621603041

unconnected · 2019-01-02, 17:36

59-digit factor of near-repdigit (691*10³⁰⁰-7)/9 was found by ECM

Code:

Using B1=43000000, B2=240490660426, polynomial Dickson(12), sigma=3032066922
Step 1 took 382110ms
Step 2 took 101223ms
********** Factor found in step 2: 21601138366813705693033870951386003818115059066377541324921
Found probable prime factor of 59 digits: 21601138366813705693033870951386003818115059066377541324921
Composite cofactor 1416732463683710775182530542771135815901595515342842856966117614129678227859411077172659990398292541537568243400899333336769174248499204974915626874899 has 151 digits

Happy New Year everyone!

bsquared · 2019-01-02, 18:10

Quote:

Originally Posted by unconnected

59-digit factor of near-repdigit (691*10³⁰⁰-7)/9 was found by ECM

Code:

Using B1=43000000, B2=240490660426, polynomial Dickson(12), sigma=3032066922
Step 1 took 382110ms
Step 2 took 101223ms
********** Factor found in step 2: 21601138366813705693033870951386003818115059066377541324921
Found probable prime factor of 59 digits: 21601138366813705693033870951386003818115059066377541324921
Composite cofactor 1416732463683710775182530542771135815901595515342842856966117614129678227859411077172659990398292541537568243400899333336769174248499204974915626874899 has 151 digits

Happy New Year everyone!

Possibly the largest of the year so far :)

VictordeHolland · 2019-01-07, 07:18

Code:

P-1 found a factor in stage #2, B1=2000000, B2=40000000, E=6.
M55715311 has a factor: 7239753241433926010086285741758451306831 (P-1, B1=2000000, B2=40000000, E=6)

40 digit factor, not composite :).

petrw1 · 2019-01-11, 22:48

https://www.mersenne.org/report_expo...xp_hi=58184849

LaurV · 2019-01-12, 05:28

not really twins (difference of 10), and generally, you can't factor a prime...

nomead · 2019-01-12, 07:05

Heh. Which sort of reminds me, I kinda shot myself in the foot a week ago. I was LL double checking a few exponents and decided to run TF a bit further just for the heck of it ...and found a factor on one of them. Some CPU time wasted, but more saved, as it wasn't even halfway through at that point.

M51202189

It even had some (old? low bounds?) P-1 work done on it, but then again, mersenne.ca says that min. B1 is 20,857 and min. B2 10,925,329,931 so maybe it was just one of those hard to find factors.

2019-01-07, 07:18	#459
VictordeHolland "Victor de Hollander" Aug 2011 the Netherlands 3²×131 Posts	Code: P-1 found a factor in stage #2, B1=2000000, B2=40000000, E=6. M55715311 has a factor: 7239753241433926010086285741758451306831 (P-1, B1=2000000, B2=40000000, E=6) 40 digit factor, not composite :).

2019-01-11, 22:48	#460
petrw1 1976 Toyota Corona years forever! "Wayne" Nov 2006 Saskatchewan, Canada 2·3·887 Posts	Factored twin primes https://www.mersenne.org/report_expo...xp_hi=58184849

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2018-08-17, 13:19	#452
Nooks Jul 2018 19 Posts	ECM on a C213, the last divisor of (3410^229-61)/9 with sigma=1:3941682105: Using B1=2900000000, B2=82640965106716, polynomial Dickson(30), sigma=1:3941682105 [...] ********* Factor found in step 2: 35020442769329876367522852735060830348867981850170604303099578467 Found prime factor of 65 digits: 35020442769329876367522852735060830348867981850170604303099578467 Prime cofactor 6463948784722816185901384621852688761921664616020783901443547268726228461664676485561963639543974467240297445194995726733180417921657435498535243769 has 148 digits The factor was found on the 25th curve; taking into account all the other cores running curves this was the 2400th curve of only 9600 I planned to run before handing the problem to CADO-NFS, so I'm counting myself quite lucky!

2019-01-12, 05:28	#461
LaurV Romulan Interpreter "name field" Jun 2011 Thailand 2⁴·643 Posts	not really twins (difference of 10), and generally, you can't factor a prime...

2019-01-12, 07:05	#462
nomead "Sam Laur" Dec 2018 Turku, Finland 317 Posts	Heh. Which sort of reminds me, I kinda shot myself in the foot a week ago. I was LL double checking a few exponents and decided to run TF a bit further just for the heck of it ...and found a factor on one of them. Some CPU time wasted, but more saved, as it wasn't even halfway through at that point. M51202189 It even had some (old? low bounds?) P-1 work done on it, but then again, mersenne.ca says that min. B1 is 20,857 and min. B2 10,925,329,931 so maybe it was just one of those hard to find factors.