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 A074545 #18 Sep 08 2022 08:45:07
%S A074545 3,18,134,1080,8978,75888,649154,5606640,48811778,427774608,
%T A074545 3769260674,33358388400,296270827778,2638754846928,23555015544194,
%U A074545 210638693637360,1886253119486978,16909812213784848,151723048895171714
%N A074545 a(n) = 2^n + 7^n + 9^n.
%H A074545 Vincenzo Librandi, <a href="/A074545/b074545.txt">Table of n, a(n) for n = 0..200</a>
%H A074545 <a href="/index/Rec">Index entries for linear recurrences with constant coefficients</a>, signature (18,-95,126).
%F A074545 From _Mohammad K. Azarian_, Dec 28 2008: (Start)
%F A074545 G.f.: 1/(1-2*x) + 1/(1-7*x) + 1/(1-9*x).
%F A074545 E.g.f.: exp(2*x) + exp(7*x) + exp(9*x). (End)
%F A074545 a(n) = 18*a(n-1) - 95*a(n-2) + 126*a(n-3).
%t A074545 Table[2^n + 7^n + 9^n, {n, 0, 20}]
%t A074545 LinearRecurrence[{18,-95,126},{3,18,134},20] (* _Harvey P. Dale_, Apr 13 2019 *)
%o A074545 (Magma) [ 2^n + 7^n + 9^n: n in [0..30]]; // _Vincenzo Librandi_, Jun 13 2011
%Y A074545 Cf. A001550, A001576, A034513, A001579, A074501 - A074580.
%K A074545 easy,nonn
%O A074545 0,1
%A A074545 _Robert G. Wilson v_, Aug 23 2002