cp's OEIS Frontend

A289688 Numbers k such that k!6 - 12 is prime, where k!6 is the sextuple factorial number (A085158).

%I A289688 #14 Nov 29 2018 16:28:36
%S A289688 11,13,23,29,35,37,49,95,97,101,113,133,137,361,401,701,1027,1331,
%T A289688 2087,2743,7781,9391,12787,12797,16123,17317,21701,49657,64661,72149,
%U A289688 86413
%N A289688 Numbers k such that k!6 - 12 is prime, where k!6 is the sextuple factorial number (A085158).
%C A289688 Corresponding primes are: 43, 79, 21493, 623633, 21827563, 49579063, 104463111013, ...
%C A289688 a(32) > 10^5.
%C A289688 Terms > 49 correspond to probable primes.
%H A289688 Henri & Renaud Lifchitz, <a href="http://www.primenumbers.net/prptop/searchform.php?form=n!6-12&amp;action=Search">PRP Records. Search for n!6-12.</a>
%H A289688 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 A289688 OpenPFGW Project, <a href="http://sourceforge.net/projects/openpfgw/">Primality Tester</a>
%e A289688 13!6 - 12 = 13*7*1 - 12 = 79 is prime, so 13 is in the sequence.
%t A289688 MultiFactorial[n_, k_] := If[n < 1, 1, n*MultiFactorial[n - k, k]];
%t A289688 Select[Range[8, 50000], PrimeQ[MultiFactorial[#, 6] - 12] &]
%Y A289688 Cf. A007661, A037082, A084438, A123910, A242994.
%K A289688 nonn,more
%O A289688 1,1
%A A289688 _Robert Price_, Jul 09 2017
%E A289688 a(29)-a(31) from _Robert Price_, Aug 03 2018