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 A115254 #4 Oct 04 2014 11:42:59
%S A115254 1,1,3,7,19,52,162,505,1666,5576,19135,66494,234316,833620,2992817,
%T A115254 10822802,39395434,144207387,530534468,1960521470,7273963575,
%U A115254 27085625086,101188629692,379160330195,1424634014730,5366319233160
%N A115254 Diagonal sums of correlation triangle for Catalan numbers.
%C A115254 Diagonal sums of number triangle A115253.
%C A115254 Convolution of A161006 and A079978. - _R. J. Mathar_, Oct 04 2014
%F A115254 G.f.: c(x)c(x^2)/(1-x^3) where c(x) is the g.f. of A000108; a(n)=sum{k=0..floor(n/2), sum{j=0..n-k, [j<=k]*C(k-j)[j<=n-2k]*C(n-2k-j)}}.
%K A115254 easy,nonn
%O A115254 0,3
%A A115254 _Paul Barry_, Jan 18 2006