A032356 Numbers k such that 13*2^k+1 is prime.

2, 8, 10, 20, 28, 82, 188, 308, 316, 1000, 28280, 38008, 43856, 88018, 109258, 114296, 521306, 562456, 684560, 1038896, 1499876, 1861732, 4998362, 5523860, 6481780, 8989858

Offset

1,1

Links

Table of n, a(n) for n=1..26.

Ray Ballinger, Proth Search Page

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

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

Mathematica

Select[Range[1000], PrimeQ[13*2^#+1] &] (* Amiram Eldar, Dec 12 2018 *)

Prog

(PARI) is(n)=ispseudoprime(13*2^n+1) \\ Charles R Greathouse IV, May 22 2017

Crossrefs

Cf. A002257.

Sequence in context: A195582 A071388 A209202 * A114272 A193266 A108468

Adjacent sequences: A032353 A032354 A032355 * A032357 A032358 A032359

Keyword

nonn,hard,more

Author

James R. Buddenhagen

Extensions

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

a(23) from http://www.prothsearch.com/riesel1.html by Robert Price, Dec 12 2018

a(24) from Jeppe Stig Nielsen, Jan 24 2020

a(25)-a(26) from Jeppe Stig Nielsen, Dec 21 2024

Status

approved