A032470 Numbers k such that 187*2^k+1 is prime.

6, 12, 48, 82, 126, 186, 732, 1926, 2802, 6712, 10026, 16062, 17790, 18156, 67878, 176316, 194950, 231112, 239832, 494602, 497926, 693012, 788640, 2249974

Offset

1,1

Links

Table of n, a(n) for n=1..24.

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

Maple

select(k->isprime(187*2^k+1), [$0..1000]); # Muniru A Asiru, Dec 18 2018

Mathematica

Select[Range[1000], PrimeQ[187*2^# + 1] & ] (* Robert Price, Dec 18 2018 *)

Prog

(PARI) is(n)=ispseudoprime(187*2^n+1) \\ Charles R Greathouse IV, Jun 13 2017

Crossrefs

Sequence in context: A105863 A052904 A106692 * A342302 A018809 A226882

Adjacent sequences: A032467 A032468 A032469 * A032471 A032472 A032473

Keyword

nonn,hard,more

Author

N. J. A. Sloane.

Extensions

a(16)-a(23) from the Ray Ballinger and Wilfrid Keller link by Robert Price, Dec 18 2018

a(24) from Jeppe Stig Nielsen, Apr 19 2020

Status

approved