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 A074604 #26 Jan 16 2024 08:33:20
%S A074604 2,11,85,737,6577,59081,531505,4783097,43046977,387421001,3486785425,
%T A074604 31381061657,282429540577,2541865836521,22876792471345,
%U A074604 205891132127417,1853020188917377,16677181699797641,150094635297261265
%N A074604 a(n) = 2^n + 9^n.
%H A074604 Vincenzo Librandi, <a href="/A074604/b074604.txt">Table of n, a(n) for n = 0..200</a>
%H A074604 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (11,-18).
%F A074604 a(n) = 9*a(n-1) - 2^n.
%F A074604 a(n) = 11*a(n-1) - 18*a(n-2), with a(0) = 2, a(1) = 11.
%F A074604 From _Mohammad K. Azarian_, Jan 02 2009: (Start)
%F A074604 G.f.: 1/(1-2*x) + 1/(1-9*x).
%F A074604 E.g.f.: exp(2*x) + exp(9*x). (End)
%t A074604 Table[2^n + 9^n, {n, 0, 25}]
%t A074604 LinearRecurrence[{11,-18},{2,11},26] (* _Harvey P. Dale_, Feb 28 2022 *)
%o A074604 (Magma) [2^n + 9^n: n in [0..35]]; // _Vincenzo Librandi_, Apr 30 2011
%o A074604 (SageMath) [2^n+9^n for n in range(31)] # _G. C. Greubel_, Jan 16 2024
%Y A074604 Cf. A000051, A007689, A034472, A034474, A034491, A052539, A062394.
%Y A074604 Cf. A062395, A062396, A063376, A063481, A074600 - A074624.
%K A074604 easy,nonn
%O A074604 0,1
%A A074604 _Robert G. Wilson v_, Aug 25 2002