20130403, 00:53  #1 
Jun 2003
Ottawa, Canada
3·17·23 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
19·23^{2} 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
79 Posts 
Congratulations, Jeff!

20130403, 02:05  #4 
Bemusing Prompter
"Danny"
Dec 2002
California
3^{2}·277 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
10051_{10} 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
4482_{10} 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
3^{2}·277 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
10011101000011_{2} Posts 

20130403, 19:23  #9 
Account Deleted
"Tim Sorbera"
Aug 2006
San Antonio, TX USA
11×389 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
2×3^{3}×83 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
495_{16} 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! 
Thread Tools  
Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
Mp: factors of p1 and p+1  paulunderwood  Miscellaneous Math  10  20130213 20:35 
Missing factors at the 'Known Factors' page  MatWurS530113  PrimeNet  11  20090121 19:08 
New factors on F12 or bug  jocelynl  Factoring  2  20041031 02:55 
New factors?  Yogi  Math  9  20041026 17:14 
The factors of 11,199  Jeff Gilchrist  NFSNET Discussion  2  20040927 23:40 