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 A122887 #3 Mar 30 2012 18:36:59
%S A122887 1,10,118,1656,27326,520626,11271436,273613032,7365210840,
%T A122887 217823497200,7022714928604,245186433880584,9217032342988575,
%U A122887 371216529334562246,15948164256621353088,728062466187371268960,35197679178007576031784
%N A122887 An upper diagonal of table A122888.
%o A122887 (PARI) {a(n)=local(F=x+x^2, G=x+x*O(x^(n+1))); if(n<3, 0, for(i=1, n-2, G=subst(F, x, G)); return(polcoeff(G, n+0, x)))}
%Y A122887 Cf. A122888; A122892.
%K A122887 nonn
%O A122887 4,2
%A A122887 _Paul D. Hanna_, Sep 18 2006