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 A113372 #5 Jun 13 2017 23:21:08 %S A113372 1,7,91,1722,43764,1415799,56096733,2644883675,145131435225, %T A113372 9107198292451,644373208531066,50814103000624929,4423148359685316443, %U A113372 421540670702940409866,43680252604560889074884 %N A113372 Column 2 of triangle A113370, also equals column 0 of A113370^7. %C A113372 Column k of A113370 = column 0 of A113370^(3*k+1) for k>=0. %o A113372 (PARI) a(n)=local(A,B);A=Mat(1);for(m=2,n+3,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+3,3] %Y A113372 Cf. A113370, A113371 (column 1), A113373 (column 3). %K A113372 nonn %O A113372 0,2 %A A113372 _Paul D. Hanna_, Nov 13 2005