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 A020766 #19 Mar 26 2025 19:31:41
%S A020766 1,29,571,9521,144907,2083865,28847827,388709777,5134091323,
%T A020766 66784487561,858403625443,10928093824193,138039056180299,
%U A020766 1732402968047417,21624191213455219,268679676312195569,3325242136114316635,41014868784078912233,504410121626681853955,6187470727275006236705
%N A020766 Expansion of g.f. 1/((1-6*x)*(1-11*x)*(1-12*x)).
%H A020766 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (29,-270,792).
%F A020766 a(n) = 23*a(n-1) - 132*a(n-2) + 6^n; a(0)=1, a(1)=29. - _Vincenzo Librandi_, Mar 11 2011
%F A020766 a(n) = 6*6^n/5 - 121*11^n/5 + 24*12^n. - _R. J. Mathar_, Jul 01 2013
%F A020766 a(n) = 29*a(n-1) - 270*a(n-2) + 792*a(n-3); a(0)=1, a(1)=29, a(2)=571. - _Harvey P. Dale_, Jun 13 2015
%F A020766 From _Elmo R. Oliveira_, Mar 26 2025: (Start)
%F A020766 E.g.f.: exp(6*x)*(6 - 121*exp(5*x) + 120*exp(6*x))/5.
%F A020766 a(n) = A016175(n+1) - A016174(n+1). (End)
%t A020766 CoefficientList[Series[1/((1-6x)(1-11x)(1-12x)),{x,0,20}],x] (* or *) LinearRecurrence[{29,-270,792},{1,29,571},20] (* _Harvey P. Dale_, Jun 13 2015 *)
%Y A020766 Cf. A016174, A016175.
%K A020766 nonn,easy
%O A020766 0,2
%A A020766 _N. J. A. Sloane_
%E A020766 More terms from _Elmo R. Oliveira_, Mar 26 2025