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 A074561 #14 Sep 08 2022 08:45:07
%S A074561 3,15,77,405,2177,11925,66377,374445,2135777,12292965,71280377,
%T A074561 415819485,2437700177,14348506005,84736115177,501776304525,
%U A074561 2977992765377,17706778767045,105443373410777,628708104245565
%N A074561 a(n) = 4^n + 5^n + 6^n.
%H A074561 Vincenzo Librandi, <a href="/A074561/b074561.txt">Table of n, a(n) for n = 0..1000</a>
%H A074561 <a href="/index/Rec">Index entries for linear recurrences with constant coefficients</a>, signature (15,-74,120).
%F A074561 From _Mohammad K. Azarian_, Dec 30 2008: (Start)
%F A074561 G.f.: 1/(1-4*x) + 1/(1-5*x) + 1/(1-6*x).
%F A074561 E.g.f.: exp(4*x) + exp(5*x) + exp(6*x). (End)
%t A074561 Table[4^n + 5^n + 6^n, {n, 0, 19}]
%o A074561 (Magma) [4^n + 5^n + 6^n: n in [0..20]]; // _Vincenzo Librandi_, Aug 24 2011
%Y A074561 Cf. A001550, A001576, A034513, A001579, A074501 - A074580.
%K A074561 easy,nonn
%O A074561 0,1
%A A074561 _Robert G. Wilson v_, Aug 23 2002