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 A138273 #2 Mar 30 2012 18:37:09 %S A138273 1,2,10,78,798,9874,141282,2273730,40400466,782174594,16339339034, %T A138273 365507560686,8703242020078,219514664265570,5840845740086722, %U A138273 163388004393303378,4790811699042196754,146865803196242855938 %N A138273 Column 1 of triangle A138271; also, column 0 of matrix power A138271^2. %Y A138273 Cf. A138271; A138272, A138274; A138275. %K A138273 nonn %O A138273 0,2 %A A138273 _Paul D. Hanna_, Mar 11 2008