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

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

Offset

1,1

Links

Table of n, a(n) for n=1..13.

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

Status

approved