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 A190976 #26 Jun 11 2022 03:34:01
%S A190976 0,1,8,61,464,3529,26840,204133,1552544,11807953,89805992,683024077,
%T A190976 5194774640,39509124889,300488675192,2285382026869,17381590189376,
%U A190976 132196575434401,1005427832907080,7646832936953437,58158379996906256,442326541164389737
%N A190976 a(n) = 8*a(n-1) - 3*a(n-2), with a(0)=0, a(1)=1.
%H A190976 G. C. Greubel, <a href="/A190976/b190976.txt">Table of n, a(n) for n = 0..1000</a>
%H A190976 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (8,-3).
%F A190976 a(n) = ((4 + sqrt(13))^n - (4 - sqrt(13))^n)/(2*sqrt(13)). - _Giorgio Balzarotti_, May 28 2011
%F A190976 G.f.: x/(1 - 8*x + 3*x^2). - _Philippe Deléham_, Oct 12 2011
%F A190976 From _G. C. Greubel_, Jun 11 2022: (Start)
%F A190976 a(n) = 3^((n-1)/2)*ChebyshevU(n-1, 4/sqrt(3)).
%F A190976 E.g.f.: (1/sqrt(13))*exp(4*x)*sinh(sqrt(13)*x). (End)
%t A190976 LinearRecurrence[{8,-3}, {0,1}, 50]
%o A190976 (Magma) [n le 2 select n-1 else 8*Self(n-1) - 3*Self(n-2): n in [1..51]]; // _G. C. Greubel_, Jun 11 2022
%o A190976 (SageMath) [lucas_number1(n,8,3) for n in (0..50)] # _G. C. Greubel_, Jun 11 2022
%Y A190976 Cf. A190958 (index to generalized Fibonacci sequences).
%K A190976 nonn,easy
%O A190976 0,3
%A A190976 _Vladimir Joseph Stephan Orlovsky_, May 24 2011