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 2004-04-08, 06:45 #1 dave_0273     Oct 2003 Australia, Brisbane 2×5×47 Posts P-1 stage 2 factor I just beat my own personal record and just found a 43 digit factor during stage 2 of p-1 factoring. My previous record was 42 digits. P-1 found a factor in stage #2, B1=70000, B2=1277500. UID: dave_0273/buffy, M12215821 has a factor: 2855451057157704997579326497626590663028969 Assuming that I did the calculation correct, this is a 142 bit factor. I am interested to know if anyone has found a bigger factor using p-1. Also, I was wondering if this number is prime, I highly doubt that it is though. Last fiddled with by dave_0273 on 2004-04-08 at 07:15
 2004-04-08, 07:38 #2 hbock     Feb 2003 163 Posts Unfortunately it's not a prime : Code: 2855451057157704997579326497626590663028969 = 896774094182730749591 * 3184136423744490284159 So you found two factors in time. You can check this for example with a UBASIC program like ECMX. A list with p-1 records you can find in the ECMnet pages : http://www.loria.fr/~zimmerma/records/Pminus1.html
 2004-04-09, 02:41 #3 dave_0273     Oct 2003 Australia, Brisbane 2·5·47 Posts I just beat my own record again. Interesting that I beat it just the next day. Anyways, here is the factor.... P-1 found a factor in stage #2, B1=70000, B2=1312500. UID: dave_0273/faith, M12223199 has a factor: 264230314763760208834215981504580626343342447 It is 45 digits and weighs in at 148 bits. Could someone check for me to see if it is prime please?? Last fiddled with by dave_0273 on 2004-04-09 at 02:47
2004-04-09, 02:50   #4
nfortino

Nov 2003

16510 Posts

Quote:
 Originally Posted by dave_0273 It is 45 digits and weighs in at 148 bits. Could someone check for me to see if it is prime please??
It's not: 264230314763760208834215981504580626343342447 = 46673864303955381847 x 5661205017073505552389801

You can check them yourself at http://www.alpertron.com.ar/ECM.HTM

 2004-04-09, 03:01 #5 dave_0273     Oct 2003 Australia, Brisbane 2×5×47 Posts Thanks for that link.
 2004-04-15, 16:41 #6 nucleon     Mar 2003 Melbourne 5×103 Posts Well done Dave, you qualify for that list. I'm just not in the same ball park - my largest is 25digits: 3392287301461488893415377 for M13127581. But hey it's prime :) Is there a way to look up the data files to see if anyone else has anything bigger? -- Craig
 2004-04-15, 20:31 #7 Prime95 P90 years forever!     Aug 2002 Yeehaw, FL 3·5·499 Posts These are the 35 digit and longer factors found with prime95: 17504141 45.00 426315489966437174530195419710289226952407399 1026199 41.00 99986711862609678639226074113089334488633 14334623 39.00 563796628294674772855559264041716715663 23343809 39.00 126200820168972868753938399731010991289 15864539 37.00 5811726848289439035828246985293098183 20396191 36.00 275806877795314616777110237874197111 5480471 35.00 87590114272360866473519508282751337 13187813 35.00 63113922700063643342764849026462401 1018697 35.00 51776547638454015479754532135290881 18965599 35.00 34488602653675602192712514732427431 16026793 35.00 19929728012623917458862281965016471 20092067 35.00 13168424217984320584506969049382921
 2004-04-15, 21:23 #8 hbock     Feb 2003 163 Posts What about 6659 42.00 226211124686120782835233945344253671049543 27691 37.00 1734072082042172647364731231822850071 Both are 'smooth' enough for Prime95. (found in an old list created by Andy Steward)
 2004-04-15, 22:02 #9 Uncwilly 6809 > 6502     """"""""""""""""""" Aug 2003 101×103 Posts 100101010110012 Posts 43 and 45 would both put you on the top 10 list.
 2004-06-07, 14:50 #10 dave_0273     Oct 2003 Australia, Brisbane 47010 Posts It doesn't beat my personal best, but here is a 43 digit factor UID: dave_0273/buffy, M12889889 has a factor: 2975472867644373392513490171544511832022967 Unfortunately, it isn't prime 2975472867644373392513490171544511832022967 = 26296325190058 952183 x 113151660779173033002049 Still, I thought that it was worth mentioning. It is a 142 bit factor.
2004-06-07, 21:27   #11
ET_
Banned

"Luigi"
Aug 2002
Team Italia

4,813 Posts

Quote:
 Originally Posted by dave_0273 It doesn't beat my personal best, but here is a 43 digit factor UID: dave_0273/buffy, M12889889 has a factor: 2975472867644373392513490171544511832022967 Unfortunately, it isn't prime 2975472867644373392513490171544511832022967 = 26296325190058 952183 x 113151660779173033002049 Still, I thought that it was worth mentioning. It is a 142 bit factor.
How do you choose Mesennes to P-1 factoring?

Did those numbers already have their LL test (I guess so)?

Luigi

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