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 A099091 #5 Feb 19 2015 15:09:12 %S A099091 1,0,2,0,3,4,0,0,12,8,0,0,9,36,16,0,0,0,54,96,32,0,0,0,27,216,240,64, %T A099091 0,0,0,0,216,720,576,128,0,0,0,0,81,1080,2160,1344,256,0,0,0,0,0,810, %U A099091 4320,6048,3072,512,0,0,0,0,0,243,4860,15120,16128,6912,1024,0,0,0,0,0,0 %N A099091 Riordan array (1,2+3x). %C A099091 Row sums are A015518(n+1). Diagonal sums are A002447. The Riordan array (1,s+tx) defines T(n,k)=binomial(k,n-k)s^k(t/s)^(n-k). The row sums satisfy a(n)=s*a(n-1)+t*a(n-2) and the diagonal sums satisfy a(n)=s*a(n-2)+t*a(n-3). %F A099091 Number triangle T(n, k)=binomial(k, n-k)2^k*(3/2)^(n-k) Columns have g.f. (2x+3x^2)^k. %e A099091 Rows begin %e A099091 1; %e A099091 0,2; %e A099091 0,3,4; %e A099091 0,0,12,8; %e A099091 0,0,9,36,16; %K A099091 easy,nonn,tabl %O A099091 0,3 %A A099091 _Paul Barry_, Sep 25 2004