A032490 Numbers k such that 227*2^k+1 is prime.

11, 15, 35, 51, 83, 87, 99, 183, 4619, 4659, 6939, 7503, 10647, 13007, 18459, 19599, 26363, 43719, 53171, 140679, 249599, 308139, 797603, 1542323, 1786779

Offset

1,1

Links

Table of n, a(n) for n=1..25.

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

Ray Ballinger, Proth Search Page

Mathematica

Select[Range[1000], PrimeQ[227*2^# + 1] & ] (* Robert Price, Dec 19 2018 *)

Prog

(PARI) is(n)=ispseudoprime(227*2^n+1) \\ Charles R Greathouse IV, Jun 13 2017

Crossrefs

Sequence in context: A085597 A316643 A097512 * A068483 A357626 A241679

Adjacent sequences: A032487 A032488 A032489 * A032491 A032492 A032493

Keyword

nonn,hard,more

Author

N. J. A. Sloane.

Extensions

a(20)-a(25) from the Ray Ballinger and Wilfrid Keller link by Robert Price, Dec 19 2018

Status

approved