91 riesel
 

91 is completed from 210000 to 300000, & prime for 245989!

Harvey563

:cool:

Speaking of 91...
 

Number 91 on the top 5000 is now [B]9*2^828709-1[/B], which was proven prime earlier today! :banana:

The k=9 search had been primeless for 6 months.

Other recent finds:
129*2^292573-1
129*2^310619-1
129*2^314188-1
129*2^331384-1

Congrats on a big, top-100 prime! :cool:

k=231 checked through n=310000 and is prime for
231*2^205017-1
231*2^224297-1
231*2^248359-1

Tests on 237 and 241 going on ...

EDIT: I stop 231 at n=310k

EDIT2: Attached is the sieve file with the numbers not tested yet to n=500k for k=231

Recent Progress
 

Recently found primes and achieved limits are given below.

k=55: 397941 [400000]
k=71: 735802 prover's code L97 [736000]
k=79: 369535 [370000]
k=89: 369628 [380000]

Is anybody interested in working on k=231 using pre-sieved values kindly provided by Keller above? If so, please announce your intentions in this thread. And please report primes (if any) by including "15k Search" in your prover's code.

I'll take up the k=231 values and report back.
(looks like n goes up to 400k and not 500k.
I'll finish LLR up to 400k and sieve if it's still promising).

Found a prime with 231:

k=231: 345183 [complete to 318k]

k=75
 

Seems as if no one is currently looking at [B]k=75[/B] (formerly tested by keller up to n=250000).
So, I'll take it a bit higher. Please let me know, if someone else has already choosen that k.

-- Thomas11

By the way: [B]k=29[/B] is tested through [B]n=1.2M[/B] now! :showoff:

231*2^369583-1 is prime

231 is now complete to 400k and continuing.

-Larry

Nice big one
 

Here is a note from Chris Caldwell's list:

220a 15*2^568780-1 171222 L52 2005

That is my second big prime from k=15 and my largest yet!

Regards

Robert Smith