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