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 A124817 #2 Mar 30 2012 18:59:18 %S A124817 1,1,3,4,12,18,55,88,273,455,1428,2448,7752,13566,43263,76912,246675, %T A124817 444015,1430715,2601300,8414640,15426840,50067108,92431584,300830572, %U A124817 558685348,1822766520,3402497504,11124755664,20858916870,68328754959 %N A124817 Interpolation of A001764(n+1) and A006629(n). %C A124817 A column of number triangle A124816. %F A124817 a(n)=(1/(2(n+3)))*C(3n/2+3,n/2+1)(1+(-1)^n)+(2/(n+3))*C(3(n+1)/2,(n-1)/2)(1-(-1)^n) %K A124817 easy,nonn %O A124817 0,3 %A A124817 _Paul Barry_, Nov 08 2006