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 A015551 #39 Sep 08 2022 08:44:40
%S A015551 0,1,6,41,276,1861,12546,84581,570216,3844201,25916286,174718721,
%T A015551 1177893756,7940956141,53535205626,360916014461,2433172114896,
%U A015551 16403612761681,110587537144566,745543286675801,5026197405777636
%N A015551 Expansion of x/(1 - 6*x - 5*x^2).
%C A015551 Let the generator matrix for the ternary Golay G_12 code be [I|B], where the elements of B are taken from the set {0,1,2}. Then a(n)=(B^n)_1,2 for instance. - _Paul Barry_, Feb 13 2004
%C A015551 Pisano period lengths: 1, 2, 4, 4, 1, 4, 42, 8, 12, 2, 10, 4, 12, 42, 4, 16, 96, 12, 360, 4, ... - _R. J. Mathar_, Aug 10 2012
%H A015551 Vincenzo Librandi, <a href="/A015551/b015551.txt">Table of n, a(n) for n = 0..1000</a>
%H A015551 Lucyna Trojnar-Spelina, Iwona Włoch, <a href="https://doi.org/10.1007/s40995-019-00757-7">On Generalized Pell and Pell-Lucas Numbers</a>, Iranian Journal of Science and Technology, Transactions A: Science (2019), 1-7.
%H A015551 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (6,5).
%F A015551 a(n) = 6*a(n-1) + 5*a(n-2).
%F A015551 a(n) = sqrt(14)*(3+sqrt(14))^n/28 - sqrt(14)*(3-sqrt(14))^n/28. - _Paul Barry_, Feb 13 2004
%t A015551 Join[{a=0,b=1},Table[c=6*b+5*a;a=b;b=c,{n,100}]] (* _Vladimir Joseph Stephan Orlovsky_, Jan 16 2011 *)
%t A015551 CoefficientList[Series[x/(1-6x-5x^2),{x,0,20}],x] (* or *) LinearRecurrence[ {6,5},{0,1},30] (* _Harvey P. Dale_, Oct 30 2017 *)
%o A015551 (Sage) [lucas_number1(n,6,-5) for n in range(0, 21)] # _Zerinvary Lajos_, Apr 24 2009
%o A015551 (Magma) I:=[0,1]; [n le 2 select I[n] else 6*Self(n-1)+5*Self(n-2): n in [1..30]]; // _Vincenzo Librandi_, Nov 14 2011
%o A015551 (PARI) a(n)=([0,1; 5,6]^n*[0;1])[1,1] \\ _Charles R Greathouse IV_, Oct 03 2016
%Y A015551 Cf. A001076, A006190, A007482, A015520, A015521, A015523, A015524, A015525, A015528, A015529, A015530, A015531, A015532, A015533, A015534, A015535, A015536, A015537, A015440, A015441, A015443, A015444, A015445, A015447, A015548, A030195, A053404, A057087, A057088, A057089, A083858, A085939, A090017, A091914, A099012, A135030, A135032, A180222, A180226, A180250.
%K A015551 nonn,easy
%O A015551 0,3
%A A015551 _Olivier Gérard_