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 A135869 #2 Mar 30 2012 18:37:07
%S A135869 1,1,6,117,6642,1097874,537135948,784812995973,3435153688724346,
%T A135869 45086429284345043334,1775007791598340247784372,
%U A135869 209630197234751724563143145346,74271350069687203431923556331222068
%N A135869 G.f. A(x) = 1 + x*A(3x)^2.
%C A135869 Self-convolution equals A135870.
%o A135869 (PARI) {a(n)=local(A=1+x+x*O(x^n));for(i=0,n,A=1+x*subst(A,x,3*x)^2);polcoeff(A,n)}
%Y A135869 Cf. A135867, A135870.
%K A135869 nonn
%O A135869 0,3
%A A135869 _Paul D. Hanna_, Dec 02 2007