A032457 Numbers k such that 161*2^k+1 is prime.

3, 5, 11, 13, 51, 53, 63, 71, 103, 179, 205, 267, 351, 589, 719, 1453, 3703, 7935, 10851, 15151, 16013, 20319, 65475, 66083, 105269, 181059, 186347, 319875, 1057743, 1668927, 1754223, 2142431

Offset

1,1

Links

Table of n, a(n) for n=1..32.

Ray Ballinger, Proth Search Page

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

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[161*2^# + 1] & ] (* Robert Price, Dec 18 2018 *)

Prog

(PARI) is(n)=ispseudoprime(161*2^n+1) \\ Charles R Greathouse IV, Jun 13 2017

Crossrefs

Sequence in context: A147568 A359303 A006794 * A122564 A162876 A162875

Adjacent sequences: A032454 A032455 A032456 * A032458 A032459 A032460

Keyword

nonn,hard,more

Author

N. J. A. Sloane.

Extensions

a(25)-a(31) from the Ray Ballinger and Wilfrid Keller link by Robert Price, Dec 18 2018

a(32) from Jeppe Stig Nielsen, May 30 2020

Status

approved