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 A111468 #4 Dec 05 2013 19:57:05 %S A111468 1,3,14,56,280,1872,11760,104832,1224720,12545280,96526080,1163289600, %T A111468 13891046400,200222668800,2917119744000,47259168768000, %U A111468 738275586048000,13386781384704000,259936372452556800,5427242941317120000 %N A111468 Leading diagonal of A111467. %Y A111468 Cf. A111467, A111469. %K A111468 easy,nonn %O A111468 1,2 %A A111468 _Amarnath Murthy_, Aug 05 2005 %E A111468 More terms from _David Wasserman_, Feb 10 2009