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 A123306 #3 Mar 30 2012 18:36:59 %S A123306 1,1,2,6,26,156,1234,12340,150994,2204112,37617314,738465620, %T A123306 16451763834,411281292920,11427727238034,350040470610996, %U A123306 11736423864328466,428080429306305136,16893650334361392866 %N A123306 Column 0 of triangle A123305. %C A123306 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 shift left equals column 0 of T^2. %Y A123306 Cf. A123305; A123307, A123308, A123309; A123310, A123311. %K A123306 nonn %O A123306 0,3 %A A123306 _Paul D. Hanna_, Sep 24 2006