A032380 Numbers k such that 61*2^k + 1 is prime.

4, 12, 48, 88, 168, 3328, 172428, 285652, 4749928

Offset

1,1

Links

Table of n, a(n) for n=1..9.

Ray Ballinger, Proth Search Page

Y. Gallot, Proth.exe: Windows Program for Finding Large Primes

Wilfrid Keller, List of primes k.2^n - 1 for k < 300

Prime Pages, Database Search Output

Index entries for sequences of n such that k*2^n-1 (or k*2^n+1) is prime

Prog

(Magma) [n: n in [1..3500] |IsPrime(61*2^n + 1)] // Vincenzo Librandi, Nov 20 2010
(PARI) is(n)=ispseudoprime(61*2^n+1) \\ Charles R Greathouse IV, Jun 13 2017

Crossrefs

Sequence in context: A022016 A151441 A361428 * A057346 A255230 A253087

Adjacent sequences: A032377 A032378 A032379 * A032381 A032382 A032383

Keyword

nonn,hard

Author

James R. Buddenhagen

Extensions

More terms (from http://web.archive.org/web/20161028080239/http://www.prothsearch.net/riesel.html), Joerg Arndt, Apr 07 2013

a(9) communicated by Jeppe Stig Nielsen, Feb 25 2024

Status

approved