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 A113371 #5 Jun 13 2017 23:21:10 %S A113371 1,4,28,326,5702,136724,4226334,161385532,7378504140,394404094270, %T A113371 24193638303234,1677962100799727,129990908689219749, %U A113371 11135889051081255518,1046032727101344902679,106966601176207198837104 %N A113371 Column 1 of triangle A113370, also equals column 0 of A113370^4. %C A113371 Column k of A113370 = column 0 of A113370^(3*k+1) for k>=0. %o A113371 (PARI) a(n)=local(A,B);A=Mat(1);for(m=2,n+2,B=matrix(m,m); for(i=1,m, for(j=1,i,if(i<3 || j==i || j>m-1,B[i,j]=1,if(j==1, B[i,1]=1,B[i,j]=(A^(3*j-2))[i-j+1,1]));));A=B);A[n+2,2] %Y A113371 Cf. A113370, A113372 (column 2), A113373 (column 3). %K A113371 nonn %O A113371 0,2 %A A113371 _Paul D. Hanna_, Nov 13 2005