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A221911 9^n + 9*n. 1
1, 18, 99, 756, 6597, 59094, 531495, 4783032, 43046793, 387420570, 3486784491, 31381059708, 282429536589, 2541865828446, 22876792455087, 205891132094784, 1853020188851985, 16677181699666722, 150094635296999283 (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 (11,-19,9).

FORMULA

G.f.: (1+7*x-80*x^2)/((1-x)^2*(1-9*x)).

a(n) = 11*a(n-1)-19*a(n-2)+9*a(n-3).

MATHEMATICA

Table[(9^n + 9 n), {n, 0, 25}] (* or *) CoefficientList[Series[(1 + 7 x - 80 x^2)/((1 - x)^2 (1 - 9 x)), {x, 0, 30}], x]

LinearRecurrence[{11, -19, 9}, {1, 18, 99}, 20] (* Harvey P. Dale, Aug 18 2014 *)

PROG

(MAGMA) [9^n + 9*n: n in [0..25]]; /* or */ I:=[1, 18, 99]; [n le 3 select I[n] else 11*Self(n-1)-19*Self(n-2)+9*Self(n-3): n in [1..30]];

(PARI) a(n)=9^n+9*n \\ Charles R Greathouse IV, Apr 18 2013

CROSSREFS

Cf. A198399.

Sequence in context: A044269 A044650 A008920 * A263999 A087638 A231144

Adjacent sequences:  A221908 A221909 A221910 * A221912 A221913 A221914

KEYWORD

nonn,easy

AUTHOR

Vincenzo Librandi, Mar 03 2013

STATUS

approved

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Last modified July 30 07:58 EDT 2021. Contains 346348 sequences. (Running on oeis4.)