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A242994 Numbers n such that n!3 - 3 is prime, where n!3 = n!!! is a triple factorial number (A007661).

%I A242994 #25 Oct 12 2014 11:25:02
%S A242994 5,10,11,13,16,22,28,71,74,94,119,121,134,157,200,262,286,484,1039,
%T A242994 1045,1190,1595,1679,1772,1789,2410,2920,5039,7919,10462,11846,23293,
%U A242994 26705,30781,43694
%N A242994 Numbers n such that n!3 - 3 is prime, where n!3 = n!!! is a triple factorial number (A007661).
%C A242994 Large terms correspond to probable primes. - _Jens Kruse Andersen_, Aug 19 2014
%C A242994 a(36) > 50000. - _Robert Price_, Oct 12 2014
%H A242994 OpenPFGW Project, <a href="http://sourceforge.net/projects/openpfgw/">Primality Tester</a>
%H A242994 Henri & Renaud Lifchitz, <a href="http://www.primenumbers.net/prptop/searchform.php?form=n!3-3&amp;action=Search">PRP Records. Search for n!3-3</a>
%e A242994 11!3-3 = 11*8*5*2-3 = 877 is prime, so 11 is in the sequence. - _Jens Kruse Andersen_, Aug 19 2014
%t A242994 MultiFactorial[n_, k_] := If[n < 1, 1, If[n < k + 1, n, n*MultiFactorial[n - k, k]]];
%t A242994 lst={};Do[If[PrimeQ[MultiFactorial[n, 3] - 3], AppendTo[lst, n]], {n, 100}];lst
%Y A242994 Cf. A007661, A037082, A084438, A243078.
%K A242994 nonn,more
%O A242994 1,1
%A A242994 _Robert Price_, Aug 17 2014
%E A242994 Links and crossrefs fixed by _Jens Kruse Andersen_, Aug 19 2014
%E A242994 a(35) from _Robert Price_, Oct 12 2014