mersenneforum.org Super Cullen & Woodall primes
 Register FAQ Search Today's Posts Mark Forums Read

 2017-09-27, 01:28 #1 Citrix     Jun 2003 110001100112 Posts Super Cullen & Woodall primes Super Cullen and Woodall defined as:- C(n)= n*2^(n*n)+1 W(n)= n*2^(n*n)-1 Primes so far 1*2^1-1 1*2^1+1 2*2^4-1 5*2^25+1 9*2^81+1 I think there are finite number of these primes, but I still wanted to search further. I have checked these up to 5 Million bits and plan to search further. I am using srsieve to sieve these numbers. Is there a faster sieve software or can gcwsieve be made faster for these numbers?
 2017-10-26, 09:12 #2 Citrix     Jun 2003 3·232 Posts I have completed this to 8M bits. Continuing. I am using the following code to sieve. Does anyone have any suggestions on how to make this faster? Thanks. Code: //Adapted from multisieve void SuperCullenWoodallSieve::DoWork64Bit(uint64_t thePrime) { uint32_t nmin, nmax; nmin = 100; nmax = 32768; uint64_t temp, power; temp = thePrime + 1; temp >> 1; temp = expmod62(temp, nmax*nmax, thePrime); power = expmod62(2, 2 * nmax, thePrime); for (int x = nmax; x >= nmin; x--) { if (temp == x) LogFactor('-', x, 2, thePrime); if (temp == thePrime - x) LogFactor('+', x, 2, thePrime); temp = mulmod62(temp, power, thePrime); if (temp&1) { temp = temp + thePrime; } temp >> 1; if (power&1) { power = power + thePrime; } power >> 1; if (power&1) { power = power + thePrime; } power >> 1; } }

 Similar Threads Thread Thread Starter Forum Replies Last Post rogue And now for something completely different 40 2020-12-08 13:21 em99010pepe Factoring 9 2019-03-26 08:35 rogue And now for something completely different 13 2014-12-29 19:11 jasong jasong 9 2008-01-25 01:51 jasong Marin's Mersenne-aries 1 2007-11-18 23:17

All times are UTC. The time now is 23:23.

Tue Jan 18 23:23:42 UTC 2022 up 179 days, 17:52, 0 users, load averages: 1.43, 1.52, 1.42