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Old 2014-02-10, 02:19   #848
prgamma10
 
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Jan 2013

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Quote:
Originally Posted by Miszka View Post
My personal best
M31051 has a factor: 24523881623890845010007531389564120430998338703 (154,1 bits)
ECM found a factor in curve #24, stage #2
Sigma=3677350809829694, B1=3000000, B2=300000000
Tasty factor, considering the ECM bounds used.

Last fiddled with by prgamma10 on 2014-02-10 at 02:22
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Old 2014-02-10, 03:18   #849
blahpy
 
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Quote:
Originally Posted by Miszka View Post
My personal best
M31051 has a factor: 24523881623890845010007531389564120430998338703 (154,1 bits)
ECM found a factor in curve #24, stage #2
Sigma=3677350809829694, B1=3000000, B2=300000000
Very nice!
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Old 2014-02-12, 00:36   #850
lycorn
 
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Quote:
Originally Posted by Miszka View Post
M31051 has a factor: 24523881623890845010007531389564120430998338703
Very nice one. It´s not every day that one finds factors for numbers this small...

Last fiddled with by lycorn on 2014-02-12 at 00:36
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Old 2014-03-09, 11:03   #851
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Hello,

IIRC this is my second biggest "regular P-1 factor":
P-1 found a factor in stage #2, B1=620000, B2=12710000, E=12.
M67894507 has a factor: 118932379415737719145680729417648731019161 (136.44 Bits)
k = 875861573129455959859026072739940 = 2 * 2 * 5 * 19 * 2897 * 15667 * 214589 * 283697 * 370423 * 2251943

and this might be my biggest "regular P-1 double factor" so far:
P-1 found a factor in stage #1, B1=635000.
M66012833 has a factor: 25442648702559071526003179150718822132839669303705434471 (184.05 Bits)

f1 = 93709867836738562740151 (76.31 Bits)
k1 = 3 * 5 * 5 * 8641 * 11071 * 98927

f2 = 271504477488809212102512933946321 (107.74 Bits)
k2 = 2 * 2 * 2 * 3 * 5 * 43 * 137 * 5737 * 27823 * 54217 * 336143


Oliver
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Old 2014-03-11, 12:17   #852
markr
 
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Those are massive - nice finds!
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Old 2014-03-26, 01:47   #853
Batalov
 
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Mar 2008
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Default how 'bout some Eisenstein-Fermat numbers?

Mike Oakes described many years ago the Eisenstein-Fermat numbers.

Mike Oakes reported that EFn are prime for 0<=n<=3, and then we have composites up to n<=19 (DC'd).
Here are some more eliminations:
Code:
1814704020258817 | 3^(2^20)-3^(2^19)+1
449939767297 | 3^(2^21)-3^(2^20)+1
EF22 LLR test is in progress (most likely known C)
EF23 LLR test is in progress (most likely known C)
841781914632193 | 3^(2^24)-3^(2^23)+1
10871635969 | 3^(2^25)-3^(2^24)+1
EF26 ??
3819992499879937 | 3^(2^27)-3^(2^26)+1
EF28 ??
156071646883479553 | 3^(2^29)-3^(2^28)+1
...
5566277615617 | 3^(2^32)-3^(2^31)+1
131985100920324097 | 3^(2^34)-3^(2^33)+1
39582418599937 | 3^(2^38)-3^(2^37)+1
(you can easily see that factors are of restricted form. Not too hard to find.)
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Old 2014-04-01, 20:56   #854
Sergiosi
 
Jun 2013

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From one of my aliquot sequences:

Using B1=3000000, B2=5706890290, polynomial Dickson(6), sigma=1045294942
Step 1 took 5593ms
Step 2 took 2784ms
********** Factor found in step 2: 7709785821798716085231895649922705932140748936402071
Found probable prime factor of 52 digits: 7709785821798716085231895649922705932140748936402071
Probable prime cofactor (679244561234214691156167254744998224687295035638998699333453501573680827350025562911300646832911553455921867383084123581660457/55577579143)/7709785821798716085231895649922705932140748936402071 has 64 digits
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Old 2014-04-02, 09:45   #855
ET_
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Quote:
Originally Posted by Sergiosi View Post
From one of my aliquot sequences:

Using B1=3000000, B2=5706890290, polynomial Dickson(6), sigma=1045294942
Step 1 took 5593ms
Step 2 took 2784ms
********** Factor found in step 2: 7709785821798716085231895649922705932140748936402071
Found probable prime factor of 52 digits: 7709785821798716085231895649922705932140748936402071
Probable prime cofactor (679244561234214691156167254744998224687295035638998699333453501573680827350025562911300646832911553455921867383084123581660457/55577579143)/7709785821798716085231895649922705932140748936402071 has 64 digits
The cofactor is a certified prime.

Luigi
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Old 2014-04-16, 19:25   #856
alpertron
 
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At this moment I'm running p-1 algorithm with B1=10M, B2=500M in the range 900000-1000000.

My computer found a new personal record:

P-1 found a factor in stage #2, B1=10000000, B2=500000000, E=12.
M985979 has a factor: 208259944761322336790033394725144178055361063

More details about this Mersenne number at: http://www.mersenne.ca/exponent/985979
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Old 2014-05-22, 00:41   #857
lycorn
 
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A somehow unexpected finding from my old snail:

UID: lycorn/snail, M947857 has a factor: 4558968051813269609

61.983 bits
K=2^2 × 601220444093 => P-1 had obviously missed it...
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Old 2014-06-11, 21:41   #858
PageFault
 
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My first ECM find:

Code:
[Wed Jun 11 22:35:04 2014]
ECM found a factor in curve #6, stage #1
Sigma=1167748058492201, B1=50000, B2=5000000.
UID: PageFault/boxen_40, M9178789 has a factor: 64337196736770344347561
k = 2^2 × 3 × 5 × 17 × 61 × 373 × 151010767

May there be many more ...
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