%I #6 Jun 05 2017 23:09:22

%S 2,4,14,28,34,46,50,52,86,100,106,140,166,170,208,242,338,344,412,

%T 1360,2024,2948,3650,5608,5744,7618,8410,8834,11872,12514,13636,18742,

%U 20846,29750,31312

%N Numbers k such that k!6 + 9 is prime, where k!6 is the sextuple factorial number (A085158 ).

%C Corresponding primes are: 11, 13, 233, 394249, 13404169, 24663654409, 311607296009, ...

%C a(36) > 50000.

%C Terms > 50 correspond to probable primes.

%H Henri & Renaud Lifchitz, <a href="http://www.primenumbers.net/prptop/searchform.php?form=n!6+9&amp;action=Search">PRP Records. Search for n!6+9.</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>

%e 14!6 + 9 = 14*8*2 + 9 = 233 is prime, so 14 is in the sequence.

%t MultiFactorial[n_, k_] := If[n < 1, 1, n*MultiFactorial[n - k, k]];

%t Select[Range[0, 50000], PrimeQ[MultiFactorial[#, 6] + 9] &]

%Y Cf. A007661, A037082, A084438, A123910, A242994.

%K nonn,more

%O 1,1

%A _Robert Price_, Jun 05 2017