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 A102923 #4 Mar 30 2012 18:36:44
%S A102923 1,7,85,2369,127796,11417607,1536493698,292107021267,74862835208823,
%T A102923 24954353268384100,10517125257007205287,5477412008465124456814,
%U A102923 3459179319447147792978276,2607366906177104506271124036
%N A102923 Row sums of triangle A102920, which equals the matrix square of A102098.
%C A102923 Triangle A102098 shifts each column up 1 row under matrix cube.
%o A102923 (PARI) {a(n)=local(A=matrix(2,2),B);A[1,1]=1; for (m=2,n+1,B=matrix(m,m);for (i=1,m, for (j=1,i, if(j==i,B[i,j]=j,B[i,j]=(A^3)[i-1,j]);));A=B); return(sum(k=0,n,(A^2)[n+1,k+1]))}
%Y A102923 Cf. A102920, A102098.
%K A102923 nonn
%O A102923 0,2
%A A102923 _Paul D. Hanna_, Jan 21 2005