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 A015548 #44 Mar 28 2025 15:24:25
%S A015548 0,1,5,37,245,1669,11285,76453,517685,3505861,23741525,160777957,
%T A015548 1088788085,7373275909,49931836565,338138493733,2289874507445,
%U A015548 15507034462021,105013666399445,711152745541477,4815927724500725,32613471569001349
%N A015548 Expansion of x/(1 - 5*x - 12*x^2).
%H A015548 Vincenzo Librandi, <a href="/A015548/b015548.txt">Table of n, a(n) for n = 0..1000</a>
%H A015548 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (5,12).
%F A015548 a(n) = 2*A099919(n-1) + 1, for n>=1.
%F A015548 a(n) = 5 a(n-1) + 12 a(n-2).
%t A015548 Join[{a=0,b=1},Table[c=5*b+12*a;a=b;b=c,{n,100}]] (* _Vladimir Joseph Stephan Orlovsky_, Jan 16 2011 *)
%t A015548 LinearRecurrence[{5, 12}, {0, 1}, 30] (* _Vincenzo Librandi_, Nov 13 2012 *)
%t A015548 CoefficientList[Series[x/(1-5x-12x^2),{x,0,30}],x] (* _Harvey P. Dale_, May 27 2023 *)
%o A015548 (Sage) [lucas_number1(n,5,-12) for n in range(0, 21)] # _Zerinvary Lajos_, Apr 24 2009
%o A015548 (Magma) [n le 2 select n-1 else 5*Self(n-1) + 12*Self(n-2): n in [1..30]]; // _Vincenzo Librandi_, Nov 13 2012
%o A015548 (PARI) x='x+O('x^30); concat([0], Vec(x/(1-5*x-12*x^2))) \\ _G. C. Greubel_, Jan 16 2018
%Y A015548 Cf. A015564 (binomial transform).
%K A015548 nonn,easy
%O A015548 0,3
%A A015548 _Olivier Gérard_