A032477 Numbers k such that 201*2^k+1 is prime.

3, 4, 9, 60, 72, 75, 84, 348, 592, 1348, 1380, 1632, 1855, 2335, 4528, 9813, 17103, 28935, 34023, 100459, 243544, 281865, 371844, 648792, 812035, 886480, 2080464

Offset

1,1

Links

Table of n, a(n) for n=1..27.

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[201*2^# + 1] & ] (* Robert Price, Dec 19 2018 *)

Prog

(PARI) is(n)=ispseudoprime(201*2^n+1) \\ Charles R Greathouse IV, Jun 13 2017

Crossrefs

Sequence in context: A225467 A225473 A015240 * A073015 A364376 A240546

Adjacent sequences: A032474 A032475 A032476 * A032478 A032479 A032480

Keyword

nonn,hard,more

Author

N. J. A. Sloane.

Extensions

a(20)-a(26) from the Ray Ballinger and Wilfrid Keller link by Robert Price, Dec 19 2018

a(27) from Jeppe Stig Nielsen, May 30 2020

Status

approved