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 A110594 #22 Jun 29 2023 11:32:12
%S A110594 4,12,48,192,768,3072,12288,49152,196608,786432,3145728,12582912,
%T A110594 50331648,201326592,805306368,3221225472,12884901888,51539607552,
%U A110594 206158430208,824633720832,3298534883328,13194139533312,52776558133248
%N A110594 a(1) = 4, a(2) = 12, for n>1: a(n) = 3*4^(n-1).
%H A110594 Vincenzo Librandi, <a href="/A110594/b110594.txt">Table of n, a(n) for n = 1..1000</a>
%H A110594 <a href="/index/Rec#order_01">Index entries for linear recurrences with constant coefficients</a>, signature (4).
%F A110594 a(n) = A002001(n), n>1. - _R. J. Mathar_, Aug 18 2008
%F A110594 G.f.: 4*x*(1 - x)/(1 - 4*x). - _Vincenzo Librandi_, May 29 2014
%p A110594 seq(coeff(series(4*x*(1-x)/(1-4*x),x,n+1), x, n), n = 1 .. 25); # _Muniru A Asiru_, Oct 21 2018
%t A110594 CoefficientList[Series[4 (1 - x)/(1 - 4 x), {x, 0, 40}], x] (* _Vincenzo Librandi_, May 29 2014 *)
%o A110594 (Magma) [4] cat [3*4^(n-1): n in [2..30]]; // _Vincenzo Librandi_, May 29 2014
%o A110594 (PARI) x='x+O('x^50); Vec(4*x*(1 - x)/(1 - 4*x)) \\ _G. C. Greubel_, Sep 01 2017
%o A110594 (GAP) Concatenation([4],List([2..25],n->3*4^(n-1))); # _Muniru A Asiru_, Oct 21 2018
%Y A110594 Cf. A000302, A007090, A081604, A110591, A110593.
%K A110594 easy,less,nonn
%O A110594 1,1
%A A110594 _Jonathan Vos Post_, Jul 29 2005
%E A110594 Definition corrected by _R. J. Mathar_, Aug 18 2008