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 A074555 #14 Sep 08 2022 08:45:07
%S A074555 3,16,94,586,3778,24826,165034,1105666,7450978,50450986,343000474,
%T A074555 2340300946,16018600978,109951298746,756592019914,5217760843426,
%U A074555 36054083523778,249557302572106,1729973941999354,12008256087645106
%N A074555 a(n) = 3^n + 6^n + 7^n.
%H A074555 Vincenzo Librandi, <a href="/A074555/b074555.txt">Table of n, a(n) for n = 0..1000</a>
%H A074555 <a href="/index/Rec">Index entries for linear recurrences with constant coefficients</a>, signature (16,-81,126).
%F A074555 From _Mohammad K. Azarian_, Dec 30 2008: (Start)
%F A074555 G.f.: 1/(1-3*x) + 1/(1-6*x) + 1/(1-7*x).
%F A074555 E.g.f.: exp(3*x) + exp(6*x) + exp(7*x). (End)
%t A074555 Table[3^n + 6^n + 7^n, {n, 0, 20}]
%o A074555 (Magma) [3^n + 6^n + 7^n: n in [0..20]]; // _Vincenzo Librandi_, Aug 24 2011
%Y A074555 Cf. A001550, A001576, A034513, A001579, A074501 - A074580.
%K A074555 easy,nonn
%O A074555 0,1
%A A074555 _Robert G. Wilson v_, Aug 23 2002