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 A136326 #11 Jan 11 2020 05:44:05
%S A136326 1,2,4,9,17,37,69,149,277,597,1109,2389,4437,9557,17749,38229,70997,
%T A136326 152917,283989,611669,1135957,2446677,4543829,9786709,18175317,
%U A136326 39146837,72701269,156587349,290805077,626349397,1163220309,2505397589,4652881237,10021590357
%N A136326 a(n) = a(n-1) + 4a(n-2) - 4a(n-3).
%H A136326 Harvey P. Dale, <a href="/A136326/b136326.txt">Table of n, a(n) for n = 0..1000</a>
%H A136326 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (1, 4, -4).
%F A136326 G.f.: (1+x-2*x^2+x^3)/(1-x-4*x^2+4*x^3). - _Harvey P. Dale_, Nov 27 2014
%t A136326 Join[{1},LinearRecurrence[{1,4,-4},{2,4,9},40]] (* _Harvey P. Dale_, Nov 27 2014 *)
%K A136326 nonn
%O A136326 0,2
%A A136326 _Paul Curtz_, Mar 26 2008
%E A136326 More terms from _Harvey P. Dale_, Nov 27 2014