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 A123308 #5 Jun 11 2015 14:06:59 %S A123308 1,3,18,144,1422,16848,235458,3827628,71466174,1515031920,36091609434, %T A123308 957367079244,28050237910926,901359663633000,31567805908329330, %U A123308 1198307340146774844,49060139971072916142,2156816501291429473248 %N A123308 Column 2 of triangle A123305. %C A123308 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 3 times column 2 of T^2 (matrix square of A123305). %Y A123308 Cf. A123305, A123306, A123307, A123309, A123310, A123311. %K A123308 nonn %O A123308 0,2 %A A123308 _Paul D. Hanna_, Sep 24 2006