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 A115282 #3 Mar 30 2012 18:59:13
%S A115282 1,3,3,3,10,3,3,12,12,3,3,12,19,12,3,3,12,21,21,12,3,3,12,21,28,21,12,
%T A115282 3,3,12,21,30,30,21,12,3,3,12,21,30,37,30,21,12,3,3,12,21,30,39,39,30,
%U A115282 21,12,3,3,12,21,30,39,46,39,30,21,12,3
%N A115282 Correlation triangle for the sequence 3-2*0^n.
%C A115282 Row sums are A102214. Diagonal sums are A115283. T(2n,n) is 9n+1 (A017173), the partial sums of (3-2*0^n)^2. T(2n,n)-T(2n,n+1) is 7-6*0^n.
%F A115282 G.f.: (1+2x)(1+2x*y)/((1-x)(1-x*y)(1-x^2*y)); Number triangle T(n, k)=sum{j=0..n, [j<=k]*(3-2*0^(k-j))*[j<=n-k]*(3-2*0^(n-k-j))}.
%e A115282 Triangle begins
%e A115282 1;
%e A115282 3, 3;
%e A115282 3,10, 3;
%e A115282 3,12,12, 3;
%e A115282 3,12,19,12, 3;
%e A115282 3,12,21,21,12, 3;
%e A115282 3,12,21,28,21,12,3;
%K A115282 easy,nonn,tabl
%O A115282 0,2
%A A115282 _Paul Barry_, Jan 19 2006