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A024024 3^n-n. 14
1, 2, 7, 24, 77, 238, 723, 2180, 6553, 19674, 59039, 177136, 531429, 1594310, 4782955, 14348892, 43046705, 129140146, 387420471, 1162261448, 3486784381, 10460353182, 31381059587, 94143178804, 282429536457, 847288609418 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (5,-7,3).

FORMULA

G.f.: (1-3*x+4*x^2)/((1-3*x)*(1-x)^2). - Vincenzo Librandi, Mar 06 2013

a(n) = 5*a(n-1)-7*a(n-2)+3*a(n-3). - Vincenzo Librandi, Mar 06 2013

MATHEMATICA

Table[3^n - n, {n, 0, 40}] (* or *) CoefficientList[Series[(1 - 3 x + 4 x^2)/((1 - 3 x)(1 - x)^2), {x, 0, 30}], x] (* Vincenzo Librandi, Mar 06 2013 *)

PROG

(MAGMA) [3^n - n: n in [0..35]]; // Vincenzo Librandi, May 13 2011

(MAGMA) I:=[1, 2, 7]; [n le 3 select I[n] else 5*Self(n-1)-7*Self(n-2)+3*Self(n-3): n in [1..30]]; // Vincenzo Librandi, Mar 06 2013

(PARI) a(n)=3^n-n \\ Charles R Greathouse IV, Sep 24 2015

CROSSREFS

Cf. A000325, A024050.

Sequence in context: A082047 A272483 A129020 * A027122 A132788 A109682

Adjacent sequences:  A024021 A024022 A024023 * A024025 A024026 A024027

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane.

STATUS

approved

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Last modified December 11 01:16 EST 2016. Contains 279033 sequences.