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 A135903 #2 Mar 30 2012 18:37:08 %S A135903 1,1,3,15,102,860,8548,97094,1234324,17302880,264503376,4371376170, %T A135903 77567318328,1469440535360,29578625457508,630090773216810, %U A135903 14155112389880376,334337856517696916,8280411098557369468 %N A135903 Column 0 of triangle A135902; also equals column 2 of triangle A135902 (shift right). %Y A135903 Cf. A135902; A135904, A135905. %K A135903 nonn %O A135903 0,3 %A A135903 _Paul D. Hanna_, Dec 18 2007