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 A106666 #23 Mar 14 2024 13:55:28
%S A106666 1,3,5,13,29,73,177,441,1089,2705,6705,16641,41281,102433,254145,
%T A106666 630593,1564609,3882113,9632257,23899521,59299329,147133185,365065985,
%U A106666 905799681,2247464961,5576397313,13836125185,34330115073,85179685889
%N A106666 Expansion of g.f. (1-4*x^2+2*x^3)/((1-x)*(1-2*x-2*x^2+2*x^3)).
%C A106666 Floretion Algebra Multiplication Program, FAMP Code: 1vesseq[I*J*cyc(I)] with I = + .5'ii' + .5'kk' + .5'ik' + .5'jk' + .5'ki' + .5'kj' and J = + .5'i + .5i' - .5'ii' + .5'jj' + .5'kk' + .5e
%H A106666 G. C. Greubel, <a href="/A106666/b106666.txt">Table of n, a(n) for n = 0..1000</a>
%H A106666 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (3,0,-4,2).
%F A106666 Superseeker results: a(n+1) - a(n) = A052970(n+2); a(n+2) - a(n) = A052987(n+2).
%F A106666 a(0)=1, a(n) = 2*A077937(n-1) + 1.
%t A106666 LinearRecurrence[{3,0,-4,2},{1,3,5,13},30] (* _Harvey P. Dale_, Jul 28 2015 *)
%o A106666 (Magma) R<x>:=PowerSeriesRing(Integers(), 50); Coefficients(R!( (1-4*x^2+2*x^3)/((1-x)*(1-2*x-2*x^2+2*x^3)) )); // _G. C. Greubel_, Sep 08 2021
%o A106666 (SageMath)
%o A106666 def A106666_list(prec):
%o A106666 P.<x> = PowerSeriesRing(QQ, prec)
%o A106666 return P( (1-4*x^2+2*x^3)/((1-x)*(1-2*x-2*x^2+2*x^3)) ).list()
%o A106666 A106666_list(50) # _G. C. Greubel_, Sep 08 2021
%Y A106666 Cf. A052970, A052987, A077937.
%K A106666 easy,nonn
%O A106666 0,2
%A A106666 _Creighton Dement_, May 13 2005