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 A074602 #22 May 10 2025 17:26:01
%S A074602 2,9,53,351,2417,16839,117713,823671,5765057,40354119,282476273,
%T A074602 1977328791,13841291297,96889018599,678223089233,4747561542711,
%U A074602 33232930635137,232630514118279,1628413598172593,11398895185897431
%N A074602 a(n) = 2^n + 7^n.
%H A074602 Vincenzo Librandi, <a href="/A074602/b074602.txt">Table of n, a(n) for n = 0..1000</a>
%H A074602 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (9,-14).
%F A074602 a(n) = 7*a(n-1) - 2^n = 9*a(n-1) - 14*a(n-2).
%F A074602 From _Mohammad K. Azarian_, Jan 02 2009: (Start)
%F A074602 G.f.: 1/(1-2*x) + 1/(1-7*x).
%F A074602 E.g.f.: e^(2*x) + e^(7*x). (End)
%F A074602 a(n) = 2*A016130(n)-9*A016130(n-1). - _R. J. Mathar_, Mar 10 2022
%t A074602 Table[2^n + 7^n, {n, 0, 25}]
%t A074602 LinearRecurrence[{9,-14},{2,9},20] (* _Harvey P. Dale_, May 10 2025 *)
%o A074602 (Magma) [2^n + 7^n: n in [0..35]]; // _Vincenzo Librandi_, Apr 30 2011
%Y A074602 Cf. A000051, A034472, A052539, A034474, A062394, A034491, A062395, A062396, A007689, A063376, A063481, A074600 - A074624.
%K A074602 easy,nonn
%O A074602 0,1
%A A074602 _Robert G. Wilson v_, Aug 25 2002