A058586 Numbers k such that 5*2^k + 3 is prime.

1, 2, 3, 4, 5, 7, 8, 11, 12, 18, 20, 26, 28, 32, 34, 43, 44, 50, 52, 58, 65, 66, 107, 140, 197, 274, 280, 380, 393, 506, 664, 738, 875, 944, 1016, 1547, 1548, 1687, 3938, 4066, 5165, 6258, 6402, 7067, 7413, 7967, 9441, 9922, 11106, 15077, 15548, 22647, 24780, 39168, 54868

Offset

1,2

Links

Jon Grantham, Table of n, a(n) for n = 1..74

Jon Grantham and Andrew Granville, Fibonacci primes, primes of the form 2^n-k and beyond, arXiv:2307.07894 [math.NT], 2023.

Formula

a(n) = A068713(n) + 1.

Mathematica

Do[ If[ PrimeQ[ 5*2^n + 3 ], Print[ n ] ], {n, 1, 10000} ]

Prog

(PARI) is(n)=ispseudoprime(5*2^n+3) \\ Charles R Greathouse IV, Jun 12 2017

Crossrefs

Cf. A068713.

Sequence in context: A331418 A062890 A259626 * A090467 A177202 A053868

Adjacent sequences: A058583 A058584 A058585 * A058587 A058588 A058589

Keyword

nonn

Author

Robert G. Wilson v, Dec 26 2000

Extensions

a(50)-a(53) from Michael S. Branicky, Jan 10 2023

a(54)-a(74) from Jon Grantham, Jul 30 2023

Status

approved