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2014-02-10, 02:19   #848
prgamma10

Jan 2013

109 Posts

Quote:
 Originally Posted by Miszka 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

2014-02-10, 03:18   #849
blahpy

Jun 2013

107 Posts

Quote:
 Originally Posted by Miszka 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!

2014-02-12, 00:36   #850
lycorn

Sep 2002
Oeiras, Portugal

144310 Posts

Quote:
 Originally Posted by Miszka 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

 2014-03-09, 11:03 #851 TheJudger     "Oliver" Mar 2005 Germany 45616 Posts 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
 2014-03-11, 12:17 #852 markr     "Mark" Feb 2003 Sydney 23D16 Posts Those are massive - nice finds!
 2014-03-26, 01:47 #853 Batalov     "Serge" Mar 2008 Phi(4,2^7658614+1)/2 59×157 Posts 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.)
 2014-04-01, 20:56 #854 Sergiosi   Jun 2013 2·3·13 Posts 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
2014-04-02, 09:45   #855
ET_
Banned

"Luigi"
Aug 2002
Team Italia

2×3×17×47 Posts

Quote:
 Originally Posted by Sergiosi 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

 2014-04-16, 19:25 #856 alpertron     Aug 2002 Buenos Aires, Argentina 2×11×61 Posts 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
 2014-05-22, 00:41 #857 lycorn     Sep 2002 Oeiras, Portugal 3·13·37 Posts 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...
 2014-06-11, 21:41 #858 PageFault     Aug 2002 Dawn of the Dead 5×47 Posts 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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