# Greetings from The On-Line Encyclopedia of Integer Sequences! http://oeis.org/

Search: id:a139200
Showing 1-1 of 1

%I A139200 #17 Sep 08 2022 08:45:33
%S A139200 5,11,12,16,36,41,42,47,127,136,356,829,1863,2065,2702,4509,7498
%N A139200 Numbers k such that (k!-5)/5 is prime.
%C A139200 a(16) > 3000. - _Ray G. Opao_, Oct 05 2008
%C A139200 a(18) > 25000. - _Robert Price_, Nov 20 2016
%t A139200 a = {}; Do[If[PrimeQ[(n! - 5)/5], Print[a]; AppendTo[a, n]], {n, 1, 300}]; a (* _Artur Jasinski_ *)
%o A139200 (Magma) [n: n in [5..500] | IsPrime((Factorial(n)-5) div 5)]; // _Vincenzo Librandi_, Nov 21 2016
%Y A139200 Cf. A139189, A139190, A139191, A139192, A139193, A139194, A139195, A139196, A139197, A139198.
%Y A139200 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 A139200 hard,more,nonn
%O A139200 1,1
%A A139200 _Artur Jasinski_, Apr 11 2008
%E A139200 a(13)-a(15) from _Ray G. Opao_, Oct 05 2008
%E A139200 a(16) from _Serge Batalov_, Feb 18 2015
%E A139200 a(17) from _Robert Price_, Nov 20 2016

# Content is available under The OEIS End-User License Agreement: http://oeis.org/LICENSE