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 A113345 #5 Jun 13 2017 22:50:29 %S A113345 1,2,1,5,6,1,19,39,10,1,113,327,105,14,1,966,3556,1315,203,18,1,10958, %T A113345 48659,19875,3367,333,22,1,156700,812462,357860,64750,6867,495,26,1, %U A113345 2727794,16136404,7547602,1435497,160005,12199,689,30,1 %N A113345 Matrix square of triangle A113340. %C A113345 Transforms column k of triangle A113340 into column k+1 of A113340. Also transforms column k of triangle A113350 into column k+1 of A113350. %e A113345 Matrix square A113340^2 starts: %e A113345 1; %e A113345 2,1; %e A113345 5,6,1; %e A113345 19,39,10,1; %e A113345 113,327,105,14,1; %e A113345 966,3556,1315,203,18,1; %e A113345 10958,48659,19875,3367,333,22,1; %e A113345 156700,812462,357860,64750,6867,495,26,1; %e A113345 2727794,16136404,7547602,1435497,160005,12199,689,30,1; ... %o A113345 (PARI) T(n,k)=local(A,B);A=matrix(1,1);A[1,1]=1;for(m=2,n+1,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^(2*j-1))[i-j+1,1]));));A=B);(A^2)[n+1,k+1] %Y A113345 Cf. A113340, A113346 (column 0), A113347 (column 1), A113348 (column 2), A113349 (column 3); A113350. %K A113345 nonn,tabl %O A113345 0,2 %A A113345 _Paul D. Hanna_, Nov 08 2005