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 A226511 #26 Feb 12 2024 09:39:12
%S A226511 0,3,24,147,816,4323,22344,113907,576096,2900163,14559864,72976467,
%T A226511 365413776,1828663203,9148098984,45754843827,228817265856,
%U A226511 1144215469443,5721464767704,28608486099987,143045917284336,715240046774883,3576231614934024,17881252217848947,89406543518781216
%N A226511 a(n) = 3*(5^n-3^n)/2.
%H A226511 Vincenzo Librandi, <a href="/A226511/b226511.txt">Table of n, a(n) for n = 0..300</a>
%H A226511 Max A. Alekseyev and T. Berger, <a href="http://arxiv.org/abs/1304.3780">Solving the Tower of Hanoi with Random Moves</a>. In: J. Beineke, J. Rosenhouse (eds.) The Mathematics of Various Entertaining Subjects: Research in Recreational Math, Princeton University Press, 2016, pp. 65-79. ISBN 978-0-691-16403-8
%H A226511 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (8,-15).
%F A226511 G.f.: 3*x/((1-5*x)*(1-3*x)). - _Vincenzo Librandi_, Jun 12 2013
%F A226511 a(n) = 8*a(n-1) -15*a(n-2) for n>1, a(0)=0, a(1)=3. - _Vincenzo Librandi_, Jun 12 2013
%F A226511 a(n) = A005059(n)*3 = A005058(n)*3/2.
%t A226511 CoefficientList[Series[3 x / ((1 - 5 x) (1 - 3 x)), {x, 0, 30}], x] (* _Vincenzo Librandi_, Jun 12 2013 *)
%t A226511 Table[3 (5^n - 3^n)/2, {n, 0, 25}] (* _Bruno Berselli_, Jun 12 2013 *)
%o A226511 (Magma) [(3/2)*(5^n-3^n): n in [0..30]]; // _Vincenzo Librandi_, Jun 12 2013
%Y A226511 Cf. A005058.
%K A226511 nonn,easy
%O A226511 0,2
%A A226511 _N. J. A. Sloane_, Jun 12 2013