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 A132805 #27 Feb 27 2024 03:00:42
%S A132805 0,3,21,171,1365,10923,87381,699051,5592405,44739243,357913941,
%T A132805 2863311531,22906492245,183251937963,1466015503701,11728124029611,
%U A132805 93824992236885,750599937895083,6004799503160661,48038396025285291,384307168202282325,3074457345618258603
%N A132805 A trisection of A024495.
%H A132805 Vincenzo Librandi, <a href="/A132805/b132805.txt">Table of n, a(n) for n = 0..1000</a>
%H A132805 <a href="/index/Rec">Index entries for linear recurrences with constant coefficients</a>, signature (7,8).
%F A132805 From _Philippe Deléham_, Nov 19 2007: (Start)
%F A132805 a(n) = A132804(n)/2.
%F A132805 G.f.: 3x/(1 - 7*x - 8*x^2).
%F A132805 a(n+1) = 7*a(n) + 8*a(n-1) for n >= 1, a(0)=0, a(1)=3. (End)
%F A132805 a(n) = 3*A015565(n). - _R. J. Mathar_, Aug 07 2017
%t A132805 LinearRecurrence[{7,8},{0,3},40] (* _Harvey P. Dale_, Feb 08 2015 *)
%o A132805 (Magma) [-(1/3)*(-1)^n+(1/3)*8^n: n in [0..25]]; // _Vincenzo Librandi_, Aug 10 2011
%Y A132805 Cf. A029898.
%K A132805 nonn,easy
%O A132805 0,2
%A A132805 _Paul Curtz_, Nov 18 2007