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 A099029 #2 Apr 30 2014 01:28:31 %S A099029 -1,6,-72,1608,-58080,3087648,-226762368,21986726016,-2720113657344, %T A099029 418117827310080,-78167762731812864,17465102642354817024, %U A099029 -4595978556276162551808,1406897783859319396442112 %N A099029 Main diagonal of array A099028. %K A099029 sign %O A099029 1,2 %A A099029 _Ralf Stephan_, Sep 27 2004