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 A190331 #39 Dec 23 2023 16:43:29
%S A190331 0,1,8,66,544,4484,36960,304648,2511104,20698128,170607232,1406254112,
%T A190331 11591247360,95542487104,787522391552,6491264106624,53505157636096,
%U A190331 441023789302016,3635200629688320,29963652616110592,246979622188261376,2035764282738312192
%N A190331 a(n) = 8*a(n-1) + 2*a(n-2), with a(0)=0, a(1)=1.
%C A190331 For n>0, a(n) equals the number of words of length n-1 over {0,1,...,9} in which 0 and 1 avoid runs of odd lengths. - _Milan Janjic_, Jan 08 2017
%H A190331 G. C. Greubel, <a href="/A190331/b190331.txt">Table of n, a(n) for n = 0..1000</a>
%H A190331 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (8,2).
%F A190331 G.f.: x/(1 - 8*x - 2*x^2). - _R. J. Mathar_, Nov 20 2011
%t A190331 LinearRecurrence[{8,2}, {0,1}, 50]
%o A190331 (PARI) x='x+O('x^30); concat([0], Vec(x/(1-8*x-2*x^2))) \\ _G. C. Greubel_, Jan 24 2018
%o A190331 (Magma) I:=[0,1]; [n le 2 select I[n] else 8*Self(n-1) + 2*Self(n-2): n in [1..30]]; // _G. C. Greubel_, Jan 24 2018
%K A190331 nonn,easy
%O A190331 0,3
%A A190331 _Vladimir Joseph Stephan Orlovsky_, May 24 2011