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 A285197 #14 Aug 19 2022 11:12:52
%S A285197 1,1,2,6,20,67,221,717,2294,7258,22760,70863,219353,675769,2073674,
%T A285197 6342414,19345052,58867195,178779893,542042565,1641058046,4962262306,
%U A285197 14989121072,45235277511,136407241265,411058035697,1237981634066,3726531171222,11212544793764,33723901952563
%N A285197 Expansion of (1-6*x+11*x^2-5*x^3) / ((1-x)*(1-3*x)*(1-3*x+x^2)).
%H A285197 Colin Barker, <a href="/A285197/b285197.txt">Table of n, a(n) for n = 0..1000</a>
%H A285197 M. H. Albert, M. D. Atkinson, and V. Vatter, <a href="http://arxiv.org/abs/1209.0425">Inflations of geometric grid classes: three case studies</a>, arXiv:1209.0425 [math.CO], 2012.
%H A285197 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (7,-16,13,-3).
%F A285197 From _Colin Barker_, May 01 2017: (Start)
%F A285197 a(n) = 7*a(n-1) - 16*a(n-2) + 13*a(n-3) - 3*a(n-4) for n>3.
%F A285197 a(n) = (1/2 + 3^n/2 + (2^(-n)*((3-sqrt(5))^n - (3+sqrt(5))^n)) / sqrt(5)).
%F A285197 (End)
%F A285197 2*a(n) = 1 +3^n -2*A001906(n). - _R. J. Mathar_, Aug 19 2022
%t A285197 LinearRecurrence[{7,-16,13,-3},{1,1,2,6},30] (* _Harvey P. Dale_, Apr 01 2018 *)
%o A285197 (PARI) Vec((1-6*x+11*x^2-5*x^3) / ((1-x)*(1-3*x)*(1-3*x+x^2)) + O(x^30)) \\ _Colin Barker_, May 01 2017
%Y A285197 Cf. A262600.
%K A285197 nonn,easy
%O A285197 0,3
%A A285197 _N. J. A. Sloane_, Apr 30 2017