Posts about k*10^n-1 moved to [URL="http://www.mersenneforum.org/showthread.php?t=9578"]another thread[/URL].

Please post new messages on this topic there.

New Conjectures 'R Us prime search effort
 

Hi all...

Come check out the new "Conjectures 'R Us" prime search effort [URL="http://www.mersenneforum.org/showthread.php?t=9738"]here[/URL]. There's plenty of bases and k's for everyone to search and have fun.


Gary

Check [URL="http://primes.utm.edu/primes/page.php?id=83407"]this[/URL] out... if this is part of primegrid, then we will fall to #5 I guess... (in terms of score)

[quote=Cruelty;121569]Check [URL="http://primes.utm.edu/primes/page.php?id=83407"]this[/URL] out... if this is part of primegrid, then we will fall to #5 I guess... (in terms of score)[/quote]
I don't see PrimeGrid in the prover code...though I can't imagine why someone would be searching for Woodall primes outside of PrimeGrid (since they would be duplicating a lot of work, especially the sieving work). It's roughly in the range that PrimeGrid is searching, though, so I wouldn't be surprised if it was a PrimeGrid thing, just that the finder forgot to include PrimeGrid in his prover code. (I'm sure if that's the case, though, the Prime Pages people will fix it.)

Cruelty

We can sustain this one, still 4th, but not the next larger one.

[QUOTE=Kosmaj;121588]We can sustain this one, still 4th, but not the next larger one.[/QUOTE]That is why we are all waiting for your k=7 prime :tu: + some other megabit primes are long overdue from me :wink:

Congrats to Richard (L185) on a huge prime
3139*2^3321905-1

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.

.
 

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^n-1, k*2^n+1, k*b^n+/-1)?

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).

4*3^311835-1 (148784 digits)
Attached is a list of primes for k=4 b=3.

[B]Cruelty[/B]

Congrats on a nice effort and a nice prime!

I remember that prof. Iskra had a special speed-up for
a^2*3^n+1, (n odd)

and found a number of large primes. I just found that [URL="http://www.ams.org/proc/2002-130-02/S0002-9939-01-06100-7/home.html"]his article[/URL] is now available free of charge! The Corollary 2.3 won't be difficult to implement uisng GMP...