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 A152809 #2 Mar 30 2012 18:37:15 %S A152809 1,1,5,15,49,180,685,2748,11683,52262,245357,1207538,6217803,33428738, %T A152809 187323142,1092328063,6618105311,41600580908,270931087106, %U A152809 1825820975565,12716770294407,91437668751232,678020392413506,5179601279549207 %N A152809 Column 4 of triangle A152798; a(n) = A152798(n+4,4). %F A152809 a(n) = A152798(n+3,4) + 4*A152798(n+3,5) + 6*A152798(n+3,6) + 4*A152798(n+3,7) + A152798(n+3,8) for n>0 with a(0)=1. %Y A152809 Cf. A152798; A122889, A152799, A152808. %K A152809 nonn %O A152809 0,3 %A A152809 _Paul D. Hanna_, Jan 01 2009