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 A115270 #2 Mar 30 2012 18:59:13
%S A115270 1,1,2,3,5,6,9,11,16,19,25,30,39,45,56,65,80,91,109,124,147,165,192,
%T A115270 215,249,276,315,349,396,435,489,536,600,654,726,790,874,946,1040,
%U A115270 1124,1232
%N A115270 Diagonal sums of correlation triangle for floor((n+4)/4).
%C A115270 Diagonal sums of number triangle A115268.
%F A115270 G.f.: (1+x+x^2+x^3)(1+x^2+x^4+x^6)/((1-x^4)^2*(1-x^8)^2*(1-x^3)); a(n)=sum{k=0..floor(n/2), sum{j=0..n-k, [j<=k]*floor((k-j+4)/4)*[j<=n-2k]*floor((n-2k-j+4)/4)}}.
%K A115270 easy,nonn
%O A115270 0,3
%A A115270 _Paul Barry_, Jan 18 2006