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a(n) = 4^n + 7^n + 9^n.
1

%I #18 Sep 08 2022 08:45:07

%S 3,20,146,1136,9218,76880,653186,5622896,48877058,428036240,

%T 3770308226,33362580656,296287600898,2638821947600,23555283963266,

%U 210639767346416,1886257414388738,16909829393522960,151723117614386306

%N a(n) = 4^n + 7^n + 9^n.

%H Vincenzo Librandi, <a href="/A074569/b074569.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 (20,-127,252).

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

%F G.f.: 1/(1-4*x) + 1/(1-7*x) + 1/(1-9*x).

%F E.g.f.: exp(4*x) + exp(7*x) + exp(9*x). (End)

%t Table[4^n + 7^n + 9^n, {n, 0, 20}]

%o (Magma) [4^n + 7^n + 9^n: n in [0..20]]; // _Vincenzo Librandi_, Aug 14 2011

%o (PARI) vector(20, n, n--; 4^n + 7^n + 9^n) \\ _G. C. Greubel_, Nov 08 2018

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

%K easy,nonn

%O 0,1

%A _Robert G. Wilson v_, Aug 23 2002