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 A083583 #17 Sep 08 2022 08:45:10
%S A083583 1,8,24,72,216,648,1944,5832,17496,52488,157464,472392,1417176,
%T A083583 4251528,12754584,38263752,114791256,344373768,1033121304,3099363912,
%U A083583 9298091736,27894275208,83682825624,251048476872,753145430616,2259436291848
%N A083583 a(n) = (8*3^n - 5*0^n)/3.
%H A083583 Vincenzo Librandi, <a href="/A083583/b083583.txt">Table of n, a(n) for n = 0..300</a>
%H A083583 <a href="/index/Rec#order_01">Index entries for linear recurrences with constant coefficients</a>, signature (3).
%F A083583 a(n) = (8*3^n - 5*0^n)/3.
%F A083583 G.f.: (1+5*x)/(1-3*x).
%F A083583 E.g.f.: (8*exp(3x) - 5*exp(0))/3.
%F A083583 a(n) = A005051(n-1), n > 0. - _R. J. Mathar_, Sep 17 2008
%t A083583 Join[{1},NestList[3#&,8,30]] (* _Harvey P. Dale_, Apr 08 2020 *)
%o A083583 (Magma) [(8*3^n-5*(0)^n)/3: n in [0..30]]; // _Vincenzo Librandi_, Jun 10 2011
%Y A083583 Cf. A083854.
%K A083583 easy,nonn
%O A083583 0,2
%A A083583 _Paul Barry_, May 01 2003