20130418, 05:34  #1 
Jan 2009
1/n
25_{8} Posts 
Code for testing a prime other than form 2^n1
Hello,
I thought there was a guide to entering a line in the worktodo file, but I searched and cant seem to find it. I have a candidate for a Sophia Prime of form 2^n +1 or there abouts (small number, nothing huge) and was looking to do a quick test. So is there a way to specify the form, or would I have to crunch the numbers to come up with an exponent that has decimals or something. Thanks! 
20130418, 11:59  #2 
Account Deleted
"Tim Sorbera"
Aug 2006
San Antonio, TX USA
17·251 Posts 
http://www.mersenneforum.org/showpos...33&postcount=6 shows the worktodo line formats. If you're trying to do something that's not supported by Prime95, check out PFGW or LLR.
Last fiddled with by MiniGeek on 20130418 at 12:00 
20130418, 17:37  #3 
"Serge"
Mar 2008
Phi(4,2^7658614+1)/2
3×3,041 Posts 

20130419, 03:20  #4 
Jan 2009
1/n
3×7 Posts 
Thank you MiniGeek and Batalov, been a while so I have to dust off the brain a little!

20130512, 18:35  #5 
7·1,117 Posts 
Mersenne Primes
The point of the program is that there is a special method to find primes which CAN be expressed as (2^P)1. There are definitely some prime numbers expressed as (2^P)+1 (I think for certain even P's...) but those numbers cannot use the Lucas Lehmer algorithm.
The algorithm was specially designed for Mersenne primes only. It saves an enormous amount of time over other conventional primality tests which is why all the biggest primes discovered to date are Mersenne primes. I couldn't explain the proof of the Lucas Lehmer test if I tried, but I do know it takes advantage of the fact that the binary form of a mersenne number is 111.........111, whereas your proposed candidate is 1000.........0001. 
20130512, 22:03  #6 
"Richard B. Woods"
Aug 2002
Wisconsin USA
7188_{10} Posts 

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