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 A108143 #10 Jan 21 2023 14:43:33
%S A108143 1,1,1,3,13,61,289,1371,6505,30865,146449,694875,3297061,15643981,
%T A108143 74227969,352198803,1671122065,7929183553,37622596897,178512678867,
%U A108143 847011613885,4018922793661,19069089675553,90479513970219
%N A108143 a(n)= 5*a(n-1) -a(n-2) -a(n-3).
%D A108143 Roger Bagula, Factoring Double Fibonacci Sequences, 2000
%H A108143 <a href="/index/Rec">Index entries for linear recurrences with constant coefficients</a>, signature (5,-1,-1)
%F A108143 G.f.: (1-4*x-3*x^2)/(1-5*x+x^2+x^3) [Sep 28 2009]
%t A108143 F[1] = 1; F[2] = 1; F[3] = 1; F[n__] := F[n] = 5*F[n - 1] - F[n - 2] - F[n - 3] a = Table[Abs[F[n]], {n, 1, 50}]
%t A108143 LinearRecurrence[{5,-1,-1},{1,1,1},30] (* _Harvey P. Dale_, Jan 21 2023 *)
%Y A108143 Cf. A056015, A056016.
%K A108143 nonn,easy
%O A108143 0,4
%A A108143 _Roger L. Bagula_, Jun 05 2005
%E A108143 Definition replaced by recurrence by the Associate Editors of the OEIS, Sep 28 2009