20110219, 23:03  #1 
Nov 2003
1110100100100_{2} Posts 
Typo in reported factor?
Bruce reports finding a factor of 6^3911 on the ECMNET webpage.
But unless my software is really screwing up, the factor does not divide. I am guessing that one or more digits are missing? 
20110219, 23:17  #2 
"Serge"
Mar 2008
Phi(4,2^7658614+1)/2
22270_{8} Posts 
Yep, it is 7,359.
Cofactor c224 is composite. (It must have divided a number from the list because othewise Paul's form wouldn't accept it. This sudoku puzzle was easy.) Last fiddled with by Batalov on 20110219 at 23:18 
20110220, 02:20  #3  
Jun 2005
lehigh.edu
2^{10} Posts 
Quote:
small one; seems likely that there are more to find. Too many new inputs over the weekend, when many of the labs are closed. Distracted by exam grading and _three_ new top5000 Proth primes. Plus the wind knocked out our power for two hours here today. Regards, Bruce  

20110221, 02:14  #4 
Jun 2005
lehigh.edu
2^{10} Posts 

20110221, 02:34  #5 
"Serge"
Mar 2008
Phi(4,2^7658614+1)/2
2^{3}·5^{2}·47 Posts 
A hole in one. Now, this is not a futile factor. :)
Congratulations! 
20110221, 14:33  #6  
Jun 2005
lehigh.edu
10000000000_{2} Posts 
Quote:
Code:
Magma V2.164 Mon Feb 21 2011 09:16:48 on altair1 [Seed =3370645033] [ <2, 2>, <3, 2>, <7, 2>, <11, 2>, <53, 1>, <353, 1>, <467, 1>, <779591,1>, <1057367, 1>, <15751453, 1>, <40771103, 1>, <43303219, 1>, <356236847,1>, <31186368729239, 1> ] q = 31186368729239 > 1.59e13 = B2 for the step2. Ooops. If it matters, this ran with k = 20. Sounds like this really used some GMPECM features; and I was more than just lucky with the parameters! Bruce (This is the new p69 by ecm, from 2,1822L C197.) 

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