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 A291289 #12 Mar 21 2023 15:41:21
%S A291289 2,0,0,2,0,2,2,2,4,4,6,8,10,14,18,24,32,42,56,74,98,130,172,228,302,
%T A291289 400,530,702,930,1232,1632,2162,2864,3794,5026,6658,8820,11684,15478,
%U A291289 20504,27162,35982,47666,63144,83648,110810,146792,194458,257602,341250
%N A291289 The Padovan sequence A000931 doubled.
%C A291289 Like A000931, this sequence has the property that the largest of any four consecutive terms equals the sum of the two smallest.
%H A291289 Michael De Vlieger, <a href="/A291289/b291289.txt">Table of n, a(n) for n = 0..8192</a>
%H A291289 David Nacin, <a href="https://cs.uwaterloo.ca/journals/JIS/VOL26/Nacin/nacin5.html">Van der Laan Sequences and a Conjecture on Padovan Numbers</a>, J. Int. Seq., Vol. 26 (2023), Article 23.1.2.
%H A291289 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (0,1,1).
%F A291289 G.f.: 2*(1-x^2)/(1-x^2-x^3).
%t A291289 CoefficientList[Series[2*(1 - x^2)/(1 - x^2 - x^3), {x, 0, 49}], x] (* _Michael De Vlieger_, Mar 21 2023 *)
%Y A291289 Cf. A000931.
%K A291289 nonn,easy
%O A291289 0,1
%A A291289 _N. J. A. Sloane_, Aug 29 2017