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Kosmaj 2007-07-08 00:09

Riesel Primes k*2^n-1, k<300 [Part II]
[URL=""]The original k<300 thread[/URL] was started in December 2003 and contains almost 600 posts. It is a great source of information about work already done, but I think we need a new thread for new posts.

The first post of the original thread contains some useful links to software used for primality search and to several stats pages listing all found primes. I'll continue to update that post, but almost all information is available on [URL=""]our web site[/URL] too.

Please post your new k<300 reservations, and your comments and observatons in this thread.

:exclaim: The latest search status, updated frequently, can be found [URL=""]here[/URL].


Cruelty 2007-07-08 08:26

Maybe we should close the original thread to avoid any confusion :question:

Flatlander 2007-07-08 13:34

k=35 tested to 900,000. Continuing.

kar_bon 2007-07-09 06:29

status and primes
k=209 llr at 704 k: 2 new primes:
209*2^692692-1 and 209*2^675232-1 (last prime at 60k!!!).

k=297 llr still at 581k (work next and let rest 209 a while)

Flatlander 2007-07-10 18:48

105*2^530360-1 is prime.

gd_barnes 2007-07-11 03:28

k=289 now complete to n=470K without a gap
One of the cores on my high-speed dual machine has now completed k=289 for the range of n=260K to 400K. The other core that I've temporarily stopped for other activities had previously completed the range of n=400K to n=470K so this completes it up to n=470K with no gaps. No more primes have been found since n=90201. :yucky:

This leaves a remaining gap for k=289 of n=470K to n=501991. I have now re-started the other core and it will run all the way up to n=520K to complete filling of the gap and confirm some prior testing.


kar_bon 2007-07-12 06:15

297*2^583464-1 (175643 digits)

sjtjung 2007-07-13 23:45

Brief update regarding new issue...

207 is at 583k and pausing to work on 31.
31 is on hold at 567k. Currently working on 800k and up to race with Benson.
567k-800k gap will be filled soon.


gd_barnes 2007-07-14 05:11

Status on k=289 and k=2145
I'm now complete on k=289 up to n=485K. Still no additional primes.

On k=2145, I've completed my own testing and am now testing from some sieve files given to me by Curtis. I'm now complete up to n=180K. Since my last status of n=120K, all previous primes listed on the summary site are correct and there were no additional primes found.


Flatlander 2007-07-15 13:02

[B]Reserving k = 251 from 545,000.
[/B]I'll push this low weight a bit higher; only about 10.5 candidates per 1000.

Just a thought. Is it possible for a k to stop producing primes once it has produced one or more?

Kosmaj 2007-07-15 13:59

[QUOTE=Flatlander;110416]Just a thought. Is it possible for a k to stop producing primes once it has produced one or more?[/QUOTE]

No, I think it's proven that if k has a prime for one n, then there are primes for infinitely many. But the gaps between primes can be large. See for example k=253 and k=101.

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