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 A026680 #5 Mar 30 2012 18:56:10
%S A026680 1,1,2,4,6,10,19,29,48,88,136,224,403,627,1030,1830,2860,4690,8257,
%T A026680 12947,21204,37068,58272,95340,165723,261063,426786,738352,1165138,
%U A026680 1903490,3279891,5183381,8463272,14532484,22995756,37528240
%N A026680 Sum{T(n-k,k)}, 0<=k<=[ n/2 ], T given by A026670.
%K A026680 nonn
%O A026680 0,3
%A A026680 _Clark Kimberling_