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a(n) = 3^n + 7^n + 9^n.
1

%I #16 Apr 11 2023 13:32:34

%S 3,19,139,1099,9043,76099,649819,5608699,48818083,427793779,

%T 3769318699,33358563499,296271355123,2638756433059,23555020310779,

%U 210638707953499,1886253162468163,16909812342793939,151723049282330059

%N a(n) = 3^n + 7^n + 9^n.

%H Vincenzo Librandi, <a href="/A074559/b074559.txt">Table of n, a(n) for n = 0..1000</a>

%H <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (19,-111,189).

%F From _Mohammad K. Azarian_, Dec 30 2008: (Start)

%F G.f.: 1/(1-3*x) + 1/(1-7*x) + 1/(1-9*x).

%F E.g.f.: exp(3*x) + exp(7*x) + exp(9*x). (End)

%F a(n) = 19*a(n-1) - 111*a(n-2) + 189*a(n-3). - _Wesley Ivan Hurt_, Apr 11 2023

%t Table[3^n + 7^n + 9^n, {n, 0, 20}]

%o (Magma) [3^n + 7^n + 9^n: n in [0..20]]; // _Vincenzo Librandi_, Aug 24 2011

%Y Cf. A001550, A001576, A034513, A001579, A074501 - A074580.

%K easy,nonn

%O 0,1

%A _Robert G. Wilson v_, Aug 23 2002