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 A189801 #28 Mar 08 2024 01:15:00
%S A189801 0,1,6,45,324,2349,17010,123201,892296,6462585,46806174,339000309,
%T A189801 2455257420,17782547301,128792600586,932798529225,6755924580624,
%U A189801 48930734246769,354387726706230,2566702968458301,18589707351105876,134638570822759965,975138791096512674
%N A189801 a(n) = 6*a(n-1) + 9*a(n-2), with a(0)=0, a(1)=1.
%H A189801 G. C. Greubel, <a href="/A189801/b189801.txt">Table of n, a(n) for n = 0..1000</a>
%H A189801 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (6,9).
%F A189801 G.f.: x/(1 - 6*x - 9*x^2). - _R. J. Mathar_, Nov 20 2011
%t A189801 LinearRecurrence[{6,9}, {0,1}, 50]
%o A189801 (PARI) x='x+O('x^30); concat([0], Vec(x/(1 - 6*x - 9*x^2))) \\ _G. C. Greubel_, Jan 16 2018
%o A189801 (Magma) I:=[0,1]; [n le 2 select I[n] else 6*Self(n-1) + 9*Self(n-2): n in [1..30]]; // _G. C. Greubel_, Jan 16 2018
%K A189801 nonn
%O A189801 0,3
%A A189801 _Vladimir Joseph Stephan Orlovsky_, May 24 2011