20130403, 00:53  #1 
Jun 2003
Ottawa, Canada
10010010001_{2} Posts 
Big factors
Found my biggest factor so far for a Wagstaff number:
2^9235649+1 has a factor: 153616228560877782360733142221974579132477827835600631264993134521609 [226.5 bits] 
20130403, 01:23  #2 
"Serge"
Mar 2008
Phi(4,2^7658614+1)/2
23A4_{16} Posts 
worktodo.txt:
Pminus1=1,2,8232929,1,10000,0,"3" => Code:
P1 found a factor in stage #1, B1=10000. 2^8232929+1 has a factor: 997183410304432117267065463213026379715216410911450070172292068758243 (Of course, I cheated in Pari first, by finding a few 2^p+1 that have at least five small factors. This one has two more slightly larger. Seven altogether.) 
20130403, 01:24  #3 
Mar 2003
4B_{16} Posts 
Congratulations, Jeff!

20130403, 02:05  #4 
Bemusing Prompter
"Danny"
Dec 2002
California
2×1,151 Posts 
Have you submitted them to Zimmermann's website?
http://www.loria.fr/~zimmerma/records/Pminus1.html 
20130403, 02:20  #5 
"Serge"
Mar 2008
Phi(4,2^7658614+1)/2
23A4_{16} Posts 
Composite factors are not eligible:
153616228560877782360733142221974579132477827835600631264993134521609 = 7160401272398244691 * 219902328863708115073 * 97559577016295905770143558963 The smallest of them should have been found by TF, easily: 62 bits. (Wagstaff numbers have factors of form 2kp+1, just like Mersenne's.) Let's find some even larger factors... Code:
P1 found a factor in stage #1, B1=100000. 2^8232929+1 has a factor: 8203927240046868961280630569987984778892578839825012457683394506843242760078451651993971 
20130403, 02:23  #6 
Sep 2002
Database er0rr
2^{6}·53 Posts 
Vincent TF'd Jeff's Wagstaff candidate to 61 bits
Last fiddled with by paulunderwood on 20130403 at 02:29 
20130403, 02:44  #7 
Bemusing Prompter
"Danny"
Dec 2002
California
2·1,151 Posts 
Damn. But it's pretty cool to find a factor that divides into three other ones.

20130403, 19:05  #8 
"Serge"
Mar 2008
Phi(4,2^7658614+1)/2
2^{2}·2,281 Posts 

20130403, 19:23  #9 
Account Deleted
"Tim Sorbera"
Aug 2006
San Antonio, TX USA
17×251 Posts 
Don't forget that TF to 61 bits for a number with p=9M is much harder than TF to 61 with p=64M. I think it's more like TFing p=64M to 64 bits...that still seems low, but for p=9M, maybe that's sufficient. Maybe they don't have an mfaktc equivalent. ("wfaktc"?)

20130403, 19:37  #10 
Sep 2002
Database er0rr
110101000000_{2} Posts 
Oliver has modified his GPU code and Jeff is testing it now. Vincent should be firing up a couple of Teslas soon.

20130407, 11:07  #11 
Jun 2003
Ottawa, Canada
7·167 Posts 
As Paul said, we are factoring to high bits now with the modified version of mfaktc. That P1 factor was from the last batch of p1 before I started using it.
GPU TF FTW! 
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