A032365 Numbers k such that 31*2^k+1 is prime.

8, 60, 68, 140, 216, 416, 1808, 1944, 9096, 76596, 93168, 4673544, 5560820, 8348000

Offset

1,1

Links

Table of n, a(n) for n=1..14.

Ray Ballinger, Proth Search Page

Ray Ballinger and Wilfrid Keller, List of primes k.2^n + 1 for k < 300

Chris K. Caldwell, The Prime Database: 31*2^4673544 + 1

Chris K. Caldwell, The Prime Database: 31*2^5560820 + 1

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

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

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

Prog

(PARI) is(n)=ispseudoprime(31*2^n+1) \\ Charles R Greathouse IV, Jun 12 2017

Crossrefs

Sequence in context: A186362 A285231 A264817 * A250315 A074423 A199906

Adjacent sequences: A032362 A032363 A032364 * A032366 A032367 A032368

Keyword

nonn,hard

Author

James R. Buddenhagen

Extensions

a(12) from Jeppe Stig Nielsen, Oct 14 2019

a(13) from Jeppe Stig Nielsen, Jan 29 2020

a(14) from Jeppe Stig Nielsen, Dec 22 2024

Status

approved