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 A117264 #3 Mar 30 2012 18:36:56
%S A117264 1,1,3,29,831,69107,16944055,12387543565,27116679815367,
%T A117264 177967005474840987,3503280999913078429261,
%U A117264 206872249547698485286567247,36647212198301159763279385189667
%N A117264 Self-convolution square-root of A117263.
%o A117264 (PARI) {a(n)=local(A2=vector(n+1,m,sum(k=0,m-1,3^((m-k-1)*(m+k-2)/2))));Vec(Ser(A2)^(1/2))[n+1]}
%K A117264 nonn
%O A117264 0,3
%A A117264 _Paul D. Hanna_, Mar 14 2006