mersenneforum.org Double-Check
 Register FAQ Search Today's Posts Mark Forums Read

 2016-08-29, 18:57 #1 wombatman I moo ablest echo power!     May 2013 33218 Posts Double-Check Could someone double-check the primality of 63998*297^21888-1? It passes 3, 5, 7, and 11 Fermat PRP but fails the N+1 BLS test via PFGW. I'd appreciate someone else confirming one way or the other.
 2016-08-29, 19:15 #2 Batalov     "Serge" Mar 2008 Phi(4,2^7658614+1)/2 3×43×73 Posts It is prime. Code: Using zero-padded FMA3 FFT length 28K, Pass1=448, Pass2=64, a = 3 ... Using zero-padded FMA3 FFT length 30K, Pass1=384, Pass2=80, a = 3 ... U((N+1)/11) is coprime to N! U((N+1)/3) is coprime to N! 63998*297^21888-1 is prime! (54129 decimal digits, P = 3) Time : 56.775 sec. Try -a1 -a2 (etc) options. Also, try LLR (and optionally, add FFT_Increment=1 (or 2, or 3) to llr.ini
 2016-08-29, 20:25 #3 lalera     Jul 2003 26216 Posts ./sllr64 -q63998*297^21888-1 63998*297^21888-1 is prime! (54129 decimal digits, P = 3) Time : 198.176 sec.
 2016-08-29, 20:46 #4 wombatman I moo ablest echo power!     May 2013 5×349 Posts Thanks to both of you. For full clarification, here's what I get with PFGW's "-tp" switch: Code: \$ pfgw64.exe -f0 -a1 -tp -q"63998*297^21888-1" PFGW Version 3.7.10.64BIT.20150809.Win_Dev [GWNUM 28.6] No factoring at all, not even trivial division Primality testing 63998*297^21888-1 [N+1, Brillhart-Lehmer-Selfridge] Running N+1 test using discriminant 2, base 2+sqrt(2) 63998*297^21888-1 is composite (240.1252s+0.0018s) I went ahead and used LLR to confirm that it's prime. Last fiddled with by wombatman on 2016-08-29 at 20:47

 Similar Threads Thread Thread Starter Forum Replies Last Post Unregistered Information & Answers 3 2011-10-01 04:38 opyrt Prime Sierpinski Project 3 2009-01-02 01:50 M0CZY Software 15 2008-10-30 14:20 gd_barnes No Prime Left Behind 0 2008-02-11 19:23 PhilF PrimeNet 6 2005-07-03 14:36

All times are UTC. The time now is 21:31.

Fri May 7 21:31:50 UTC 2021 up 29 days, 16:12, 1 user, load averages: 2.33, 2.60, 2.69