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 A138274 #2 Mar 30 2012 18:37:09 %S A138274 1,3,18,156,1714,22368,333910,5566728,101955050,2027241660, %T A138274 43372029642,991507256804,24084513595722,618791039789272, %U A138274 16751222781082878,476239112549941408,14179227111187986642,441017358981919297508 %N A138274 Column 2 of triangle A138271; also, column 0 of matrix power A138271^3. %Y A138274 Cf. A138271; A138272, A138273; A138275. %K A138274 nonn %O A138274 0,2 %A A138274 _Paul D. Hanna_, Mar 11 2008