mersenneforum.org Typo in reported factor?
 User Name Remember Me? Password
 Register FAQ Search Today's Posts Mark Forums Read

 2011-02-19, 23:03 #1 R.D. Silverman     Nov 2003 26·113 Posts Typo in reported factor? Bruce reports finding a factor of 6^391-1 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?
 2011-02-19, 23:17 #2 Batalov     "Serge" Mar 2008 Phi(4,2^7658614+1)/2 22·3·7·109 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 2011-02-19 at 23:18
2011-02-20, 02:20   #3
bdodson

Jun 2005
lehigh.edu

100000000002 Posts

Quote:
 Originally Posted by Batalov 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.)
Yes, sorry; and thanks. Different c27x first five hole. But another
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
---

2011-02-21, 02:14   #4
bdodson

Jun 2005
lehigh.edu

20008 Posts

Quote:
 Originally Posted by Batalov (It must have divided a number from the list because othewise Paul's form wouldn't accept it. This sudoku puzzle was easy.)
OK, how's about this one?
474942339376967475871960321762614254290810243038880418971061342256529

2nd hole. -bd

 2011-02-21, 02:34 #5 Batalov     "Serge" Mar 2008 Phi(4,2^7658614+1)/2 217048 Posts A hole in one. Now, this is not a futile factor. :-) Congratulations!
2011-02-21, 14:33   #6
bdodson

Jun 2005
lehigh.edu

210 Posts

Quote:
 Originally Posted by Batalov A hole in one. Now, this is not a futile factor. :-) Congratulations!
Here's the group order:

Code:
Magma V2.16-4     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> ]
So that's p = 356236847 < 400M = B1 for the step1 prime,
q = 31186368729239 > 1.59e13 = B2 for the step2. Ooops. If it matters,
this ran with k = 20. Sounds like this really used some GMP-ECM features;
and I was more than just lucky with the parameters!

Bruce (This is the new p69 by ecm, from 2,1822L C197.)

 Thread Tools

 Similar Threads Thread Thread Starter Forum Replies Last Post mattmill30 GPU Computing 1 2016-02-05 19:41 IvanP PrimeNet 2 2016-01-09 17:58 Chuck GPU to 72 1 2011-12-12 13:36 Siemelink Riesel Prime Search 9 2008-07-16 05:21 ppo PrimeNet 21 2008-04-20 06:21

All times are UTC. The time now is 12:03.

Wed Nov 25 12:03:58 UTC 2020 up 76 days, 9:14, 4 users, load averages: 1.86, 1.72, 1.58

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.

This forum has received and complied with 0 (zero) government requests for information.

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation.
A copy of the license is included in the FAQ.