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 A074531 #18 Sep 08 2022 08:45:07
%S A074531 3,14,94,764,6658,59324,532234,4785284,43053538,387440684,3486844474,
%T A074531 31381238804,282430072018,2541867430844,22876797254314,
%U A074531 205891146476324,1853020231964098,16677181828937804,150094635684681754
%N A074531 a(n) = 2^n + 3^n + 9^n.
%H A074531 Vincenzo Librandi, <a href="/A074531/b074531.txt">Table of n, a(n) for n = 0..200</a>
%H A074531 <a href="/index/Rec">Index entries for linear recurrences with constant coefficients</a>, signature (14,-51,54).
%F A074531 From _Mohammad K. Azarian_, Dec 27 2008: (Start)
%F A074531 G.f.: 1/(1-2*x) + 1/(1-3*x) + 1/(1-9*x).
%F A074531 E.g.f.: exp(2*x) + exp(3*x) + exp(9*x). (End)
%t A074531 Table[2^n + 3^n + 9^n, {n, 0, 20}]
%t A074531 LinearRecurrence[{14,-51,54},{3,14,94},20] (* _Harvey P. Dale_, Nov 29 2019 *)
%o A074531 (Magma) [2^n + 3^n + 9^n: n in [0..25]]; // _Vincenzo Librandi_, Jun 11 2011
%Y A074531 Cf. A001550, A001576, A034513, A001579, A074501 - A074580.
%K A074531 easy,nonn
%O A074531 0,1
%A A074531 _Robert G. Wilson v_, Aug 23 2002