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 A020720 #41 Jan 10 2025 04:39:09
%S A020720 7,9,12,16,21,28,37,49,65,86,114,151,200,265,351,465,616,816,1081,
%T A020720 1432,1897,2513,3329,4410,5842,7739,10252,13581,17991,23833,31572,
%U A020720 41824,55405,73396,97229,128801,170625,226030,299426,396655,525456,696081,922111,1221537
%N A020720 Pisot sequences E(7,9), P(7,9).
%H A020720 Colin Barker, <a href="/A020720/b020720.txt">Table of n, a(n) for n = 0..1000</a>
%H A020720 S. B. Ekhad, N. J. A. Sloane, and D. Zeilberger, <a href="http://arxiv.org/abs/1609.05570">Automated proofs (or disproofs) of linear recurrences satisfied by Pisot Sequences</a>, arXiv:1609.05570 [math.NT], 2016.
%H A020720 Yuksel Soykan, Vedat Irge, and Erkan Tasdemir, <a href="https://doi.org/10.9734/ajpas/2024/v26i12691">A Comprehensive Study of K-Circulant Matrices Derived from Generalized Padovan Numbers</a>, Asian Journal of Probability and Statistics 26 (12):152-70, (2024). See p. 154.
%H A020720 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (0,1,1).
%F A020720 a(n) = a(n-2) + a(n-3) for n>=3. (Proved using the PtoRv program of Ekhad-Sloane-Zeilberger.) - N. J. A. Sloane, Sep 09 2016
%F A020720 G.f.: (7+9*x+5*x^2) / (1-x^2-x^3). - _Colin Barker_, Jun 05 2016
%t A020720 LinearRecurrence[{0, 1, 1}, {7, 9, 12}, 50] (* _Jean-François Alcover_, Aug 31 2018 *)
%t A020720 CoefficientList[Series[(7 + 9 x + 5 x^2)/(1 - x^2 - x^3), {x, 0, 50}], x] (* _Stefano Spezia_, Aug 31 2018 *)
%Y A020720 A subsequence of A000931.
%Y A020720 See A008776 for definitions of Pisot sequences.
%Y A020720 The following are basically all variants of the same sequence: A000931, A078027, A096231, A124745, A133034, A134816, A164001, A182097, A228361 and probably A020720. However, each one has its own special features and deserves its own entry.
%K A020720 nonn,easy
%O A020720 0,1
%A A020720 _David W. Wilson_