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 A190984 #27 Dec 23 2023 09:44:34
%S A190984 0,1,9,74,603,4909,39960,325277,2647773,21553018,175442751,1428113633,
%T A190984 11624923440,94627515529,770273175681,6270065972426,51038681522067,
%U A190984 415457671891621,3381848276370120,27528430784089733,224082939122216757,1824047436611322682
%N A190984 a(n) = 9*a(n-1) - 7*a(n-2), with a(0)=0, a(1)=1.
%H A190984 G. C. Greubel, <a href="/A190984/b190984.txt">Table of n, a(n) for n = 0..1000</a>
%H A190984 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (9,-7).
%F A190984 G.f.: x/(1-9*x+7*x^2). - _Philippe Deléham_, Oct 12 2011
%F A190984 E.g.f.: (2/sqrt(53))*exp(9*x/2)*sinh(sqrt(53)*x/2). - _G. C. Greubel_, Aug 26 2022
%t A190984 LinearRecurrence[{9,-7}, {0,1}, 50]
%o A190984 (Magma) [Round(7^((n-1)/2)*Evaluate(ChebyshevU(n), 9/(2*Sqrt(7)))): n in [0..30]]; // _G. C. Greubel_, Aug 26 2022
%o A190984 (SageMath)
%o A190984 A190984 = BinaryRecurrenceSequence(9,-7,0,1)
%o A190984 [A190984(n) for n in (0..30)] # _G. C. Greubel_, Aug 26 2022
%Y A190984 Cf. A190958 (index to generalized Fibonacci sequences).
%K A190984 nonn
%O A190984 0,3
%A A190984 _Vladimir Joseph Stephan Orlovsky_, May 24 2011