Riesel Primes k*2^n-1, k<300 [Was "k=1"]

[Templus]

93*2^251199-1 is prime!
Finally a newly fresh prime for me! ^^
It has 75621 digits and is submitted under prover-code L128. (LLR,15k and my username)

[Keller]

Testing k=99

[Chaos]

Can I work on k=81? It seems to be available to the webpage
I would also like to work on k=243, is that also available?

[Kosmaj]

k=81 is available from n=220k.
k=243 although it looks available has been checked by p48 and he found 3 primes for n between 387k and 744k. The exact range he checked is not known because he reports neither to us nor to Keller. It's possible that the 230-350k range was not checked.

[Chaos]

Ill work only on k=81 then. Thank you.

[Chaos]

Can I take 127 instead of 243. This one seems to be free. Thank you

[Kosmaj]

k=127 is available from n=230k. But be careful, it has very low weight, there may not be many primes there. Still, not many candidates will survive sieving so you can reach 300k or 400k quickly, and with some luck find a prime.

In any case, please keep us informed about your progress (once in a month or so or when you reach certain milestones like n=300k, 500k, or 1M, depends how far do you intend to go), and definitely when you stop working on them. Thanks and good luck!

[Thomas11]

Originally Posted by Kosmaj

In any case, please keep us informed about your progress...

29*2^1478344-1 is prime!

[Kosmaj]

Thomas, congrats on a huge prime! Can you tell us about the limits you reached for k's you work on now, IIRC you were also testing k=11?

It's a pity almost nobody reports here anymore. Masser and JCS (Sax) disappeared, although Masser reported some of his limits to Wilfrid Keller.

Now, my recently reached limits are given below, no new primes.
k=7, to n=1.3M (in progress to 2M)
k=59, in the 500-620k range (in progress to 1M)
k=87, to n=580k (in progress to 1M)
k=95, to n=440k (in progress to 700k)
k=165, to n=590k (will stop at 600k)

Also, by joint effort, k=65 was processed to n=600k.

I'd like to suggest that we create a new project k*2^n-1, k<300 (or k<250 since PrimeSearch works on some k's in the 250-300 interval) where we can report primes found with help of coordination provided by this thread since the "15k Search" is not the right project to report all such primes. Any suggestions for the project name? "k*2^n-1, k<300" is an obvious but a bit clumsy candidate, while "Riesel Primes" can be confused with "Riesel Sieve".

[Kosmaj]

If you read this please note that 97*2^n-1 is already checked to 800k. Please stop your tests from 250k and either select another k, or proceed from 800k. Thanks!

BTW, I'm now trying to update the Riesel List originally compiled by Joss. Please, kindly report your achieved limits for respective k's on the list. A partially updated list will be available in about half an hour.

[Thomas11]

Kosmaj

k=11 is tested to n=1080000.
k=29 is tested to n=1480000.

There is also a megabit-prime for k=11, which was found earlier:
11*2^1044086-1 (already on Wilfried Keller's list)