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 A135083 #2 Mar 30 2012 18:37:07
%S A135083 1,3,15,112,1128,14373,221952,4029915,84135510,1985740905,52277994396,
%T A135083 1518768476508,48261093246396,1665034362336120,61979166611850084,
%U A135083 2475861386988907814,105641851808320785498,4795101548183135826810
%N A135083 Column 2 of triangle A135080.
%C A135083 Triangle A135080 transforms diagonals in the table of coefficients of successive self-compositions of x+x^2 (cf. A122888).
%o A135083 (PARI) {a(n)=local(F=x,M,N,P); M=matrix(n+4,n+4,r,c,F=x;for(i=1,r+c-2,F=subst(F,x,x+x^2+x*O(x^(n+4))));polcoeff(F,c)); N=matrix(n+3,n+3,r,c,M[r,c]);P=matrix(n+3,n+3,r,c,M[r+1,c]);(P~*N~^-1)[n+3,3]}
%Y A135083 Cf. A135080 (triangle); other columns: A135081, A135082.
%K A135083 nonn
%O A135083 0,2
%A A135083 _Paul D. Hanna_, Nov 18 2007