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 A074613 #19 Mar 10 2023 19:21:52
%S A074613 2,11,65,407,2657,17831,121745,839927,5830337,40615751,283523825,
%T A074613 1981521047,13858064417,96956119271,678491508305,4748635251767,
%U A074613 33237225536897,232647693856391,1628482317387185,11399170063280087
%N A074613 a(n) = 4^n + 7^n.
%H A074613 G. C. Greubel, <a href="/A074613/b074613.txt">Table of n, a(n) for n = 0..1000</a>
%H A074613 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (11,-28).
%F A074613 From _Mohammad K. Azarian_, Jan 11 2009: (Start)
%F A074613 G.f.: 1/(1-4*x) + 1/(1-7*x).
%F A074613 E.g.f.: e^(4*x) + e^(7*x). (End)
%F A074613 a(n) = 11*a(n-1) - 28*a(n-2) with a(0)=2, a(1)=11. - _Vincenzo Librandi_, Jul 21 2010
%t A074613 Table[4^n + 7^n, {n, 0, 25}]
%t A074613 LinearRecurrence[{11,-28},{2,11},30] (* _Harvey P. Dale_, Oct 03 2013 *)
%o A074613 (Magma) [4^n+7^n: n in [0..30]]; // _G. C. Greubel_, Mar 10 2023
%o A074613 (SageMath) [4^n+7^n for n in range(31)] # _G. C. Greubel_, Mar 10 2023
%Y A074613 Cf. A000051, A007689, A034472, A034474, A034491, A052539, A062394.
%Y A074613 Cf. A062395, A062396, A063376, A063481, A074600 - A074624.
%K A074613 easy,nonn
%O A074613 0,1
%A A074613 _Robert G. Wilson v_, Aug 26 2002