A151913 Numbers n for which (8+n!)/8 is prime.

7, 9, 10, 12, 14, 20, 23, 24, 29, 44, 108, 2049, 3072, 4862, 8807, 15089

Offset: 1

Author

Artur Jasinski, Apr 07 2008

Keywords

• nonn

Comments

a(17) > 25000. - Robert Price, Dec 20 2016

Crossrefs

For primes of the form (8+k!!)/8 see A139066.

Cf. A089130, A117141, A139035, A139057, A139059, A139060, A139062, A139064, A139067.

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).

Programs

Mathematica

a = {}; Do[If[PrimeQ[(n! + 8)/8], AppendTo[a, n]], {n, 1, 500}]; a

PARI

is(n)=n>6 && isprime((8+n!)/8) \\ Charles R Greathouse IV, Apr 29 2016

Extensions

Definition corrected Feb 24 2010

More terms from Serge Batalov, Feb 18 2015

a(15)-a(16) from Robert Price, Dec 20 2016