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 A111977 #4 Mar 30 2012 18:36:50
%S A111977 1,2,4,13,57,369,3681,59073,1579393,72188673,5749089793,809616264193,
%T A111977 204018868459521,92907742733348865,77097057406948106241,
%U A111977 117413997231333438701569,330195264668839727287861249
%N A111977 Row sums of triangle A111975, which shifts columns left and up under matrix square.
%o A111977 (PARI) {a(n,q=2)=local(A=Mat(1),B);if(n<0,0, for(m=1,n+2,B=matrix(m,m);for(i=1,m, for(j=1,i, if(j==i,B[i,j]=1,if(j==1,B[i,j]=if(i>2,(A^q)[i-1,2],1), B[i,j]=(A^q)[i-1,j-1]));));A=B); return(sum(k=0,n,A[n+1,k+1])))}
%Y A111977 Cf. A111975 (triangle), A078537 (variant).
%K A111977 nonn
%O A111977 0,2
%A A111977 _Paul D. Hanna_, Aug 25 2005