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 A089941 #5 Dec 10 2014 14:02:10
%S A089941 1,2,4,9,19,42,90,197,424,923,1989,4315,9300,20129,43374,93724,201888,
%T A089941 435713,938218,2022972,4354569,9382489,20190181,43477688,93534469,
%U A089941 201326672,433017364,931701321,2003520121,4309597827,9265723250
%N A089941 Row sums of triangle A089940.
%F A089941 a(n)=sum{k=0..n, Bin(n+k, floor((n-k)/2))}.
%F A089941 Conjecture: +n*(n+6)*(n-5)*a(n) -(n+6)*(n^2-3*n-6)*a(n-1) -2*(n+6)*(3*n^2-20*n
%F A089941 +27)*a(n-2) +(n+6)*(3*n^2-19*n+36)*a(n-3) +2*(4*n-15)*(n-3)*(n+6)*a(n-4) +4*(n-3
%F A089941 )*(n-4)*(n+6)*a(n-5)=0. - _R. J. Mathar_, Dec 10 2014
%K A089941 easy,nonn
%O A089941 0,2
%A A089941 _Paul Barry_, Nov 16 2003