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 A074551 #16 Sep 08 2022 08:45:07
%S A074551 3,16,106,820,6898,60316,536266,4801540,43118818,387702316,3487892026,
%T A074551 31385431060,282446845138,2541934531516,22877065673386,
%U A074551 205892220185380,1853024526865858,16677199008675916,150094704403896346
%N A074551 a(n) = 3^n + 4^n + 9^n.
%H A074551 Vincenzo Librandi, <a href="/A074551/b074551.txt">Table of n, a(n) for n = 0..200</a>
%H A074551 <a href="/index/Rec">Index entries for linear recurrences with constant coefficients</a>, signature (16,-75,108).
%F A074551 From _Mohammad K. Azarian_, Dec 28 2008: (Start)
%F A074551 G.f.: 1/(1-3*x) + 1/(1-4*x) + 1/(1-9*x).
%F A074551 E.g.f.: exp(3*x) + exp(4*x) + exp(9*x). (End)
%F A074551 a(n) = 16*a(n-1) - 75*a(n-2) + 108*a(n-3).
%t A074551 Table[3^n + 4^n + 9^n, {n, 0, 20}]
%o A074551 (Magma) [3^n + 4^n + 9^n: n in [0..30]]; // _Vincenzo Librandi_, Jun 13 2011
%Y A074551 Cf. A001550, A001576, A034513, A001579, A074501 - A074580.
%K A074551 easy,nonn
%O A074551 0,1
%A A074551 _Robert G. Wilson v_, Aug 23 2002