This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A289685 #15 Nov 29 2018 17:52:05 %S A289685 17,19,23,31,37,47,65,151,157,251,283,371,391,635,779,799,1517,1799, %T A289685 3355,24619,40375,40793,53135,79427 %N A289685 Numbers k such that k!6 - 6 is prime, where k!6 is the sextuple factorial number (A085158). %C A289685 Corresponding primes are: 929, 1723, 21499, 1339969, 49579069, 42061737019, ... %C A289685 a(25) > 10^5. %C A289685 Terms > 65 correspond to probable primes. %H A289685 Henri & Renaud Lifchitz, <a href="http://www.primenumbers.net/prptop/searchform.php?form=n!6-6&action=Search">PRP Records. Search for n!6-6.</a> %H A289685 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 A289685 OpenPFGW Project, <a href="http://sourceforge.net/projects/openpfgw/">Primality Tester</a> %e A289685 17!6 - 6 = 17*11*5 - 6 = 929 is prime, so 17 is in the sequence. %t A289685 MultiFactorial[n_, k_] := If[n < 1, 1, n*MultiFactorial[n - k, k]]; %t A289685 Select[Range[6, 50000], PrimeQ[MultiFactorial[#, 6] - 6] &] %Y A289685 Cf. A007661, A037082, A084438, A123910, A242994. %K A289685 nonn,more %O A289685 1,1 %A A289685 _Robert Price_, Jul 09 2017 %E A289685 a(23)-a(24) from _Robert Price_, Aug 03 2018