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%I #8 Sep 27 2014 06:10:36
%S 2,4,5,8,10,11,14,20,23,32,34,46,47,62,136,179,208,209,229,311,340,
%T 406,692,1235,1349,2558,2651,2873,3794,7417,8647,8695,10004,13595,
%U 18658,21427,23120,43316
%N Numbers n such that n!3 + 3^3 is prime.
%C Large terms correspond to probable primes.
%C a(39) > 50000.
%H Henri & Renaud Lifchitz, <a href="http://www.primenumbers.net/prptop/searchform.php?form=n!3+27&action=Search">PRP Records. Search for n!3+27</a>
%H Joe McLean, <a href="http://web.archive.org/web/20091027034731/http://uk.geocities.com/nassarawa%40btinternet.com/probprim2.htm">Interesting Sources of Probable Primes</a>
%H OpenPFGW Project, <a href="http://sourceforge.net/projects/openpfgw/">Primality Tester</a>
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/Multifactorial.html">Multifactorial.</a>
%e 10!3+27 = 10*7*4*1+27= 307 is prime, so 10 is in the sequence.
%t MultiFactorial[n_, k_] := If[n < 1, 1, If[n < k + 1, n, n*MultiFactorial[n - k, k]]];
%t lst={};Do[If[PrimeQ[MultiFactorial[n, 3] + 27], AppendTo[lst, n]], {n, 100}];lst
%Y Cf. A007661, A037082, A084438, A243078.
%K nonn,more
%O 1,1
%A _Robert Price_, Sep 25 2014
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