A090703 Numbers k such that k*k! + 1 is prime.

1, 2, 3, 4, 5, 7, 12, 19, 23, 45, 58, 149, 151, 197, 682, 879, 1134, 1906, 6616, 10242

Offset

1,2

Links

Table of n, a(n) for n=1..20.

Formula

a(n) = A049432(n)-1.

Example

3*3!+1 = 19 and 19 is prime, so 3 is a member.

Mathematica

Do[If[PrimeQ[n*n! + 1], Print[n]], {n, 0, 2000}] (* Mohammed Bouayoun (mohammed.bouayoun(AT)sanef.com), May 05 2006 *)

Prog

(PARI) isok(k) = ispseudoprime(k*k! + 1); \\ Altug Alkan, Mar 22 2018

Crossrefs

Cf. A049432.

Sequence in context: A240732 A060437 A133428 * A352820 A137357 A100676

Adjacent sequences: A090700 A090701 A090702 * A090704 A090705 A090706

Keyword

nonn,more

Author

mohammed bouayoun (bouyao(AT)wanadoo.fr), Jan 15 2004

Extensions

a(17) from Mohammed Bouayoun (mohammed.bouayoun(AT)sanef.com), May 05 2006

a(18)-a(19) from Jason Earls, Jan 24 2008

a(20) from Seiichi Manyama (by using the data calculated by Donovan Johnson, Dec 18 2009), Mar 22 2018

Status

approved