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 A026397 #12 Jun 13 2015 00:49:06
%S A026397 1,2,3,6,10,17,31,53,92,163,282,492,863,1501,2621,4582,7987,13946,
%T A026397 24354,42489,74179,129497,226000,394523,688670,1202020,2098239,
%U A026397 3662553,6392969,11159290,19478867,34000750,59349706,103596641
%N A026397 Sum{T(n-k,k)}, 0<=k<=[ n/2 ], where T is the array in A026386.
%H A026397 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (0,1,3,1).
%F A026397 Pairwise sums of A026385. - _Ralf Stephan_, Jul 22 2003
%F A026397 G.f.: [(1+x)(1+x+x^2)]/[1-x^2-3x^3-x^4]. - _Ralf Stephan_, Apr 30 2004
%t A026397 LinearRecurrence[{0,1,3,1},{1,2,3,6},40] (* _Harvey P. Dale_, Apr 15 2015 *)
%K A026397 nonn
%O A026397 0,2
%A A026397 _Clark Kimberling_