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 A097336 #8 Jun 13 2015 00:51:30
%S A097336 1,5,5,21,101,181,517,2133,5029,13301,47429,127893,340709,1099573,
%T A097336 3145861,8597205,26190373,76524149,214079429,633125397,1857511781,
%U A097336 5282782645,15412788997,45132977493,129657499813,376262123765
%N A097336 Sum k=0..n, C(n-k, floor(k/2))4^k.
%C A097336 The sequence sum{k=0..n, C(n-k,floor(k/2))r^k} has g.f. (1+rx)/(1-x-r^2x^3).
%H A097336 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,16)
%F A097336 G.f. : (1+4x)/(1-x-16x^3); a(n)=a(n-1)+16a(n-3).
%t A097336 LinearRecurrence[{1,0,16},{1,5,5},30] (* _Harvey P. Dale_, Sep 15 2011 *)
%Y A097336 Cf. A097333, A097334, A097335.
%K A097336 easy,nonn
%O A097336 0,2
%A A097336 _Paul Barry_, Aug 05 2004