A032412 Numbers k such that 125*2^k+1 is prime.

1, 5, 7, 17, 25, 35, 67, 281, 331, 491, 581, 941, 1205, 1279, 1411, 1631, 1895, 2735, 3475, 13955, 50491, 68819, 423155, 432719, 507637, 701981, 924085, 1107425, 2071555, 2369461, 5149981

Offset

1,2

Links

Table of n, a(n) for n=1..31.

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[125*2^# + 1] & ] (* Robert Price, Dec 17 2018 *)

Prog

(PARI) is(n)=ispseudoprime(125*2^n+1) \\ Charles R Greathouse IV, Jun 13 2017

Crossrefs

Sequence in context: A025085 A175238 A240030 * A114970 A048710 A126142

Adjacent sequences: A032409 A032410 A032411 * A032413 A032414 A032415

Keyword

nonn,more

Author

James R. Buddenhagen

Extensions

a(23)-a(29) from the Ray Ballinger and Wilfrid Keller link by Robert Price, Dec 17 2018

a(30) from Jeppe Stig Nielsen, Apr 04 2020

a(31) from Jeppe Stig Nielsen, Dec 23 2024

Status

approved