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 A102100 #4 Mar 30 2012 18:36:44
%S A102100 1,3,18,322,12979,924628,103158338,16710522378,3724631345923,
%T A102100 1097090407192683,413803244841678483,194887616017161359389,
%U A102100 112265654949194591311618,77751843768367000711311005
%N A102100 Row sums of triangular matrix A102098, which shifts upward to exclude the main diagonal under matrix cube.
%o A102100 (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,if(j==1,B[i,j]=(A^3)[i-1,1], B[i,j]=(A^3)[i-1,j]));));A=B); return(sum(k=0,n,A[n+1,k+1]))}
%Y A102100 Cf. A102098, A102099.
%K A102100 nonn
%O A102100 0,2
%A A102100 _Paul D. Hanna_, Dec 29 2004