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 A103287 #3 Mar 30 2012 18:36:45
%S A103287 1,2,5,12,30,77,202,540,1464,4014,11101,30910,86542,243416,687364,
%T A103287 1947736,5536216,15779646,45088304,129124925,370550378,1065368994,
%U A103287 3068348448,8851297414,25571726480,73981434516,214317561452
%N A103287 Main diagonal of triangle A103286, in which row n+1 is formed by sorting, in ascending order, the result of the convolution of row n with {2,1}.
%F A103287 a(n) ~ 3^n*log_3(n)/(18n) (conjecture).
%o A103287 (PARI) {a(n)=local(A=vector(n+1,i,vector(i)),B);A[1][1]=1; for(k=1,n,B=vector(k+1);B[1]=2*A[k][1];B[k+1]=A[k][k]; for(i=2,k,B[i]=2*A[k][i]+A[k][i-1]); A[k+1]=vecsort(B));return(A[n+1][n+1])}
%Y A103287 Cf. A103286, A103285.
%K A103287 nonn
%O A103287 0,2
%A A103287 _Paul D. Hanna_, Jan 28 2005