%I #54 Nov 20 2016 10:24:05

%S 11,15,16,25,35,59,64,68,82,121,149,238,584,912,3349,4111,4324,15314,

%T 19944,20658,22740,23364

%N Numbers k for which (7+k!)/7 is prime.

%C For primes of the form (7+k!)/7, see A139064.

%C a(23) > 25000. - _Robert Price_, Nov 20 2016

%t a = {}; Do[If[PrimeQ[(n! + 7)/7], AppendTo[a, n]], {n, 1, 500}]; a

%t Select[Range[500],PrimeQ[(7+#!)/7]&] (* _Harvey P. Dale_, Sep 01 2014 *)

%o (PARI) for(k=7,1e3,if(ispseudoprime(k!/7+1),print1(k", "))) \\ _Charles R Greathouse IV_, Jul 15 2011

%Y Cf. A082672, A089085, A089130, A117141, A007749, A139056, A139057, A139058, A139059, A139060, A139061, A139061, A139062, A139063, A139064, A139065, A139066, A020458.

%Y 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).

%K nonn,hard,more

%O 1,1

%A _Artur Jasinski_, Apr 07 2008

%E More terms from _Serge Batalov_, Feb 18 2015

%E a(18)-a(22) from _Robert Price_, Nov 20 2016