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a(n) = 6n + 3^n.
0

%I #14 Sep 08 2022 08:45:50

%S 9,21,45,105,273,765,2229,6609,19737,59109,177213,531513,1594401,

%T 4783053,14348997,43046817,129140265,387420597,1162261581,3486784521,

%U 10460353329,31381059741,94143178965,282429536625,847288609593

%N a(n) = 6n + 3^n.

%H <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (5, -7, 3).

%F From _R. J. Mathar_, Feb 21 2010: (Start)

%F a(n) = 5*a(n-1) - 7*a(n-2) + 3*a(n-3).

%F G.f.: -3*x*(3-8*x+x^2)/((3*x-1) * (x-1)^2). (End)

%o (Magma) [6*n+3^n: n in [1..500]] // _Vincenzo Librandi_, Dec 04 2010

%K nonn

%O 1,1

%A Mickel Tolbert (princess_rockstar34(AT)yahoo.com), Feb 17 2010

%E Extended by _R. J. Mathar_ and _Vincenzo Librandi_, Feb 21 2010