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 A152402 #2 Mar 30 2012 18:37:15 %S A152402 1,3,15,99,794,7414,78507,926026,12010188,169580899,2586371577, %T A152402 42336163519,739814864633,13739211766050,270108101356162, %U A152402 5602446487013365,122232180232983149,2797753890784828302 %N A152402 Column 2 of triangle A152400. %C A152402 Matrix powers of triangle T=A152400 satisfy: %C A152402 column k of T^(j+1) = column j of T^(k+1) for all j>=0, k>=0. %Y A152402 Cf. A152400; A127715, A152401, A152403, A152404; A152405. %K A152402 nonn %O A152402 0,2 %A A152402 _Paul D. Hanna_, Dec 05 2008