20071109, 02:30  #34 
Nov 2003
2·1,811 Posts 

20071226, 19:21  #37  
A Sunny Moo
Aug 2007
USA (GMT5)
1869_{16} Posts 
Quote:


20071226, 21:46  #38 
Nov 2003
2×1,811 Posts 
Cruelty
We can sustain this one, still 4th, but not the next larger one. 
20071227, 00:29  #39 
May 2005
2^{3}·7·29 Posts 

20080117, 00:31  #40 
Nov 2003
2×1,811 Posts 
Congrats to Richard (L185) on a huge prime
3139*2^33219051 only 3 digits shy of one million digits! He found the 9th SoB prime in 2005 (4847*2^3321063+1, 999744 digits) and is currently ranked 14th person by score. Last fiddled with by Kosmaj on 20080117 at 00:31 
20080202, 15:09  #41 
Oct 2007
3^{2}×11 Posts 
.
Prof. Cooper found another very large prime:
7 * 2^3015762+1 (907836 digits). By the way, can I somewhere find an overview how fast the different forms of numbers can be tested at the moment (for a example a comparison of the forms k*2^n1, k*2^n+1, k*b^n+/1)? Last fiddled with by Retep on 20080202 at 15:10 
20080203, 14:03  #42 
Nov 2003
E26_{16} Posts 
Yes, that's his largest prime after two Mersennes.
We are now waiting to see is it a Fermat or a GF divisor, I'm sure he is now working on those tests. As for the processing speed, when b=2, both 1 and +1 are about the same for the given k. When b>2 it's much slower (except, of course when b is a power of 2). 
20080308, 23:32  #43 
May 2005
2^{3}·7·29 Posts 
4*3^3118351 (148784 digits)
Attached is a list of primes for k=4 b=3. 
20080310, 04:55  #44 
Nov 2003
E26_{16} Posts 
Cruelty
Congrats on a nice effort and a nice prime! I remember that prof. Iskra had a special speedup for a^2*3^n+1, (n odd) and found a number of large primes. I just found that his article is now available free of charge! The Corollary 2.3 won't be difficult to implement uisng GMP... 
Thread Tools  
Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
Mersenne Primes p which are in a set of twin primes is finite?  carpetpool  Miscellaneous Math  3  20170810 13:47 
Distribution of Mersenne primes before and after couples of primes found  emily  Math  34  20170716 18:44 
Conjecture about Mersenne primes and nonprimes v2  Mickey1  Miscellaneous Math  1  20130530 12:32 
A conjecture about Mersenne primes and nonprimes  Unregistered  Information & Answers  0  20110131 15:41 
possible primes (real primes & poss.prime products)  troels munkner  Miscellaneous Math  4  20060602 08:35 