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 A074538 #19 Sep 08 2022 08:45:07
%S A074538 3,14,78,476,3042,19964,133338,901796,6155682,42307244,292241898,
%T A074538 2026156916,14085431922,98109721724,684326604858,4778079120836,
%U A074538 33385518525762,233393453571404,1632228295438218,11417968672225556,79887633730301202,559022701243584284
%N A074538 a(n) = 2^n + 5^n + 7^n.
%H A074538 Vincenzo Librandi, <a href="/A074538/b074538.txt">Table of n, a(n) for n = 0..200</a>
%H A074538 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (14,-59,70).
%F A074538 From _Mohammad K. Azarian_, Dec 27 2008: (Start)
%F A074538 G.f.: 1/(1-2*x)+1/(1-5*x)+1/(1-7*x).
%F A074538 E.g.f.: exp(2*x)+exp(5*x)+exp(7*x). (End)
%F A074538 a(n) = 14*a(n-1) - 59*a(n-2) + 70*a(n-3) for n > 2. - _Wesley Ivan Hurt_, Oct 06 2017
%p A074538 A074538:=n->2^n+5^n+7^n: seq(A074538(n), n=0..30); # _Wesley Ivan Hurt_, Oct 06 2017
%t A074538 Table[2^n + 5^n + 7^n, {n, 0, 20}]
%t A074538 LinearRecurrence[{14,-59,70},{3,14,78},20] (* _Harvey P. Dale_, Dec 21 2016 *)
%o A074538 (Magma) [2^n + 5^n + 7^n: n in [0..25]]; // _Vincenzo Librandi_, Jun 11 2011
%Y A074538 Cf. A001550, A001576, A001579, A034513, A074501 - A074580.
%K A074538 easy,nonn
%O A074538 0,1
%A A074538 _Robert G. Wilson v_, Aug 23 2002