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 A099516 #8 Jun 13 2015 00:51:33
%S A099516 0,1,2,5,10,23,50,112,246,545,1202,2658,5870,12972,28656,63315,139880,
%T A099516 309049,682790,1508527,3332850,7363430,16268356,35942447,79409300,
%U A099516 175442668,387613604,856372740,1892023992,4180136405,9235369230
%N A099516 A transform of the Pell numbers.
%C A099516 A transform of A000129 under the mapping g(x)->(1/(1+x^3))g(x/(1+x^3))
%H A099516 <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (2,1,-2,2,0,-1).
%F A099516 G.f.: x/(1-2x-x^2+2x^3-2x^4+x^6); a(n)=2a(n-1)+a(n-2)-2a(n-3)+2a(n-4)-a(n-6); a(n)=sum{k=0..floor(n/3), binomial(n-2k, k)(-1)^k*Pell(n-3k)}.
%t A099516 LinearRecurrence[{2,1,-2,2,0,-1},{0,1,2,5,10,23},40] (* _Harvey P. Dale_, Apr 15 2015 *)
%Y A099516 Cf. A099505, A099508.
%K A099516 easy,nonn
%O A099516 0,3
%A A099516 _Paul Barry_, Oct 20 2004