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 A015587 #36 Dec 18 2023 10:05:05
%S A015587 0,1,9,92,927,9355,94392,952433,9610209,96968644,978430095,9872525939,
%T A015587 99615464496,1005136965793,10142002801593,102334531838060,
%U A015587 1032572817360063,10418835206459227,105127817849093736,1060757547912895121,10703223927556087185,107997348375046630996
%N A015587 Expansion of x/(1 - 9*x - 11*x^2).
%C A015587 Pisano period lengths: 1, 3, 4, 6, 20, 12, 48, 6, 12, 60, 5, 12,168, 48, 20, 12,288, 12, 6, 60,... - _R. J. Mathar_, Aug 10 2012
%H A015587 Vincenzo Librandi, <a href="/A015587/b015587.txt">Table of n, a(n) for n = 0..1000</a>
%H A015587 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (9,11).
%F A015587 a(n) = 9*a(n-1) + 11*a(n-2).
%t A015587 Join[{a=0,b=1},Table[c=9*b+11*a;a=b;b=c,{n,40}]] (* _Vladimir Joseph Stephan Orlovsky_, Mar 29 2011 *)
%t A015587 LinearRecurrence[{9, 11}, {0, 1}, 30] (* _Vincenzo Librandi_, Nov 15 2012 *)
%o A015587 (Sage) [lucas_number1(n,9,-11) for n in range(0, 19)] # _Zerinvary Lajos_, Apr 26 2009
%o A015587 (Magma) [n le 2 select n-1 else 9*Self(n-1) + 11*Self(n-2): n in [1..30]]; // _Vincenzo Librandi_, Nov 15 2012
%o A015587 (PARI) x='x+O('x^30); concat([0], Vec(x/(1-9*x-11*x^2))) \\ _G. C. Greubel_, Jan 06 2018
%K A015587 nonn,easy
%O A015587 0,3
%A A015587 _Olivier Gérard_