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 A128329 #4 Mar 30 2012 18:37:03 %S A128329 1,1,4,30,321,4389,72512,1399755,30865353,764755508,21024535960, %T A128329 634924059276,20890221475598,743727414390456,28484480606420928, %U A128329 1167761832049224515,51022550712426870397,2366859765773183488674 %N A128329 Main diagonal of table A128325. %F A128329 a(n) = [x^n] {1 + H(x)}, where H(x) is the (n+2)-th self-composition of G(x) and G(x) = x + x*G(G(x)) is the g.f. of A030266. %o A128329 (PARI) {a(n)=local(A=1+x,B);for(i=0,n,A=1+x*A*subst(A,x,x*A+x*O(x^n))); B=A;for(i=1,n,B=subst(B,x,x*A+x*O(x^n)));polcoeff(B,n)} %Y A128329 Cf. A030266; A128325 (table), A128326 (row 1), A128327 (row 2), A128328 (row 3). %K A128329 nonn %O A128329 0,3 %A A128329 _Paul D. Hanna_, Mar 11 2007