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 A287844 #9 May 23 2025 15:20:18 %S A287844 2,4,8,10,14,16,20,22,26,34,70,164,346,398,902,938,1426,1682,1928, %T A287844 3596,3796,15058,25654,37330 %N A287844 Numbers k such that k!6 + 3 is prime, where k!6 is the sextuple factorial number (A085158 ). %C A287844 Corresponding primes are: 5, 7, 19, 43, 227, 643, 4483, 14083, 116483, 13404163, ... %C A287844 a(25) > 50000. %C A287844 Terms > 34 correspond to probable primes. %H A287844 Henri & Renaud Lifchitz, <a href="http://www.primenumbers.net/prptop/searchform.php?form=n!6+3&action=Search">PRP Records. Search for n!6+3.</a> %H A287844 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 A287844 OpenPFGW Project, <a href="http://sourceforge.net/projects/openpfgw/">Primality Tester</a> %e A287844 10!6 + 3 = 10*4 + 3 = 43 is prime, so 10 is in the sequence. %t A287844 MultiFactorial[n_, k_] := If[n < 1, 1, n*MultiFactorial[n - k, k]]; %t A287844 Select[Range[0, 50000], PrimeQ[MultiFactorial[#, 6] + 3] &] %t A287844 Select[Range[3800],PrimeQ[Times@@Range[#,1,-6]+3]&] (* The program generates the first 21 terms of the sequence. *) (* _Harvey P. Dale_, May 23 2025 *) %Y A287844 Cf. A007661, A037082, A084438, A123910, A242994. %K A287844 nonn,more %O A287844 1,1 %A A287844 _Robert Price_, Jun 01 2017