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 A158366 #5 Aug 21 2013 05:12:43 %S A158366 1,2,3,4,5,4,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26, %T A158366 27,26,29,30,31,32,33,34,35,36,37,38,39,40,41,40,43,44,43,46,47,48,49, %U A158366 50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,64,67,68,69,70,71,72 %N A158366 Least k such that n! divides (n+k)!/(n+1)!. %C A158366 Motivated by 6!=10!/7!. %C A158366 It appears that for most n, a(n) = n. The sequence of n for which a(n) != n begins: 6, 28, 42, 45, 66, 77, 91, 110, 126 ... that is probably A120624. - _Michel Marcus_, Aug 21 2013 %o A158366 (PARI) for (n=1,100,k=1;while((n+k)!/(n+1)!%n!,k++);print1(k,",")) %Y A158366 Cf. A000142. %K A158366 nonn %O A158366 1,2 %A A158366 _Jaume Oliver Lafont_, Mar 17 2009