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 A015579 #43 Dec 30 2023 23:41:43
%S A015579 0,1,9,83,765,7051,64989,599003,5521005,50887051,469025469,4323003323,
%T A015579 39845080845,367251734251,3384955769949,31199105398043,
%U A015579 287561860122285,2650454951896651,24429218287314429,225163874489623163,2075333306981237325,19128327511810382251
%N A015579 Expansion of g.f. x/(1 - 9*x - 2*x^2).
%H A015579 Vincenzo Librandi, <a href="/A015579/b015579.txt">Table of n, a(n) for n = 0..1000</a>
%H A015579 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (9,2).
%F A015579 a(n) = 9*a(n-1) + 2*a(n-2).
%F A015579 E.g.f.: 2*exp(9*x/2)*sinh(sqrt(89)*x/2)/sqrt(89). - _Stefano Spezia_, Apr 06 2023
%t A015579 Join[{a=0,b=1},Table[c=9*b+2*a;a=b;b=c,{n,60}]] (* _Vladimir Joseph Stephan Orlovsky_, Jan 27 2011 *)
%t A015579 LinearRecurrence[{9, 2}, {0, 1}, 30] (* _Vincenzo Librandi_, Nov 14 2012 *)
%t A015579 CoefficientList[Series[x/(1-9x-2x^2),{x,0,30}],x] (* _Harvey P. Dale_, Aug 14 2023 *)
%o A015579 (Sage) [lucas_number1(n,9,-2) for n in range(0, 19)] # _Zerinvary Lajos_, Apr 26 2009
%o A015579 (Magma) [n le 2 select n-1 else 9*Self(n-1) + 2*Self(n-2): n in [1..30]]; // _Vincenzo Librandi_, Nov 14 2012
%o A015579 (PARI) x='x+O('x^30); concat([0], Vec(x/(1-9*x-2*x^2))) \\ _G. C. Greubel_, Jan 06 2018
%Y A015579 Cf. A099371.
%K A015579 nonn,easy
%O A015579 0,3
%A A015579 _Olivier Gérard_
%E A015579 Extended by _T. D. Noe_, May 23 2011