A139061 Numbers n for which (4+n!)/4 is prime.

4, 5, 6, 13, 21, 25, 32, 40, 61, 97, 147, 324, 325, 348, 369, 1290, 1342, 3167, 6612, 8176, 10990

Offset

1,1

Comments

For primes of the form (4+k!)/4, see A139060.

a(22) > 25000. - Robert Price, Jan 10 2017

Links

Table of n, a(n) for n=1..21.

Mathematica

a = {}; Do[If[PrimeQ[(n! + 4)/4], AppendTo[a, n]], {n, 1, 500}]; a
Select[Range[500], PrimeQ[(4+#!)/4]&]  (* Harvey P. Dale, Mar 24 2011 *)

Prog

(PARI) for(n=4, 1e3, if(ispseudoprime(n!/4+1), print1(n", "))) \\ Charles R Greathouse IV, Jul 15 2011

Crossrefs

Cf. A082672, A089085, A089130, A117141, A007749, A139056, A139057, A139058, A139059, A139060, A139061, A139061, A139062, A139063, A139064, A139065, A139066, A020458, A139068, A137390, A139070, A139071, A139072.

Cf. n!/m-1 is a prime: A002982, A082671, A139056, A139199-A139205; n!/m+1 is a prime: A002981, A082672, A089085, A139061, A139058, A139063, A139065, A151913, A137390, A139071 (1<=m<=10).

Sequence in context: A063833 A260107 A167434 * A029645 A191208 A242077

Adjacent sequences: A139058 A139059 A139060 * A139062 A139063 A139064

Keyword

nonn

Author

Artur Jasinski, Apr 07 2008

Extensions

More terms from Serge Batalov, Feb 18 2015

a(19) - a(21) from Robert Price, Jan 10 2017

Status

approved