Congratulations! :bounce:

Very Nice:surprised

k=1222853775
 

From Choose your own k:

1222853775*2^272173-1 (81942 digits)

[QUOTE=Kosmaj][B]97*2^843205-1[/B] is prime! [253832 digits][/QUOTE]
This is quite a gap... previous prime for k=97 has been found [URL="http://primes.utm.edu/primes/page.php?id=34725"]12 years ago at n=6981[/URL] :surprised

22932195*2^217722-1 (65549 digits)

it'll be on the list for about 3 weeks :whistle:

From choose your own k:

5169615*2^267293-1 (80470 digits)

From the RPS drive:
918332415*2^294041-1 (88525 digits)

From choose your own k:

5169615*2^271290-1 (81674 digits)

97*k^n-1
 

[QUOTE=Cruelty]This is quite a gap... previous prime for k=97 has been found [URL="http://primes.utm.edu/primes/page.php?id=34725"]12 years ago at n=6981[/URL] :surprised[/QUOTE]

Guys, thanks for your kind comments. I knew that the previous prime for k=97 was at n=6981 but had no idea that it was found 12 years ago, and as I see now, by famous Mr. Dubner! It was the only [I]k[/I] with no k*2^n-1 primes for n>10000. Special thanks are due to David Broadhurst who checked k=97 in the 200-800k range, and also to Thomas Masser (60-200k) and Tom Kuechler (16-60k). The range completion details are based on Dr. Keller's [URL="http://www.prothsearch.net/riesel2.html"]records[/URL].

854917635*2^279210-1 (84060 digits)

223*2^307755-1 (92646 digits)