cp's OEIS Frontend

A289697 Numbers k such that k!6 - 24 is prime, where k!6 is the sextuple factorial number (A085158).

%I A289697 #14 Dec 01 2018 17:38:58
%S A289697 9,11,13,17,23,25,29,31,37,43,53,65,71,77,79,115,119,151,173,559,793,
%T A289697 1571,1715,1807,1861,2047,2215,3491,4751,6631,9089,9139,9253,25811,
%U A289697 29491,29495,54335,54991,66535,72365
%N A289697 Numbers k such that k!6 - 24 is prime, where k!6 is the sextuple factorial number (A085158).
%C A289697 Corresponding primes are: 3, 31, 67, 911, 21481, 43201, 623621, 1339951, ...
%C A289697 a(41) > 10^5.
%C A289697 Terms > 43 correspond to probable primes.
%H A289697 Henri & Renaud Lifchitz, <a href="http://www.primenumbers.net/prptop/searchform.php?form=n!6-24&amp;action=Search">PRP Records. Search for n!6-24.</a>
%H A289697 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 A289697 OpenPFGW Project, <a href="http://sourceforge.net/projects/openpfgw/">Primality Tester</a>
%e A289697 13!6 - 4 = 13*7*1 - 24 = 67 is prime, so 13 is in the sequence.
%t A289697 MultiFactorial[n_, k_] := If[n < 1, 1, n*MultiFactorial[n - k, k]];
%t A289697 Select[Range[9, 50000], PrimeQ[MultiFactorial[#, 6] - 24] &]
%t A289697 Select[Range[8,5000],PrimeQ[Times@@Range[#,1,-6]-24]&] (* _Harvey P. Dale_, Dec 01 2018 *)
%Y A289697 Cf. A007661, A037082, A084438, A123910, A242994.
%K A289697 nonn,more
%O A289697 1,1
%A A289697 _Robert Price_, Jul 09 2017
%E A289697 a(37)-a(40) from _Robert Price_, Aug 03 2018