

A090703


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


3



1, 2, 3, 4, 5, 7, 12, 19, 23, 45, 58, 149, 151, 197, 682, 879, 1134, 1906, 6616, 10242
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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 * A137357 A100676 A193769
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



