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 A123307 #4 Mar 30 2012 18:36:59 %S A123307 1,2,8,44,312,2776,30312,397728,6151768,110306160,2260463464, %T A123307 52304514912,1352534122104,38742215685776,1219910431007656, %U A123307 41945588389187712,1565744883592488856,63123204175617586000 %N A123307 Column 1 of triangle A123305. %C A123307 Triangle T=A123305 is defined by: (column k of T) = (k+1)*(column k of T^2) shifted to have an initial '1'; thus this sequence shifted left equals twice column 1 of T^2 (matrix square of A123305). %Y A123307 Cf. A123305; A123306, A123308, A123309; A123310, A123311. %K A123307 nonn %O A123307 0,2 %A A123307 _Paul D. Hanna_, Sep 24 2006