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A221909 7^n + 7*n. 1
1, 14, 63, 364, 2429, 16842, 117691, 823592, 5764857, 40353670, 282475319, 1977326820, 13841287285, 96889010498, 678223072947, 4747561510048, 33232930569713, 232630513987326, 1628413597910575 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..500

Index entries for linear recurrences with constant coefficients, signature (9,-15,7).

FORMULA

G.f.: (1+5*x-48*x^2)/((1-x)^2*(1-7*x)).

a(n) = 9*a(n-1)-15*a(n-2)+7*a(n-3).

a(n) = A176972(n) - 1.

MATHEMATICA

Table[(7^n + 7 n), {n, 0, 30}] (* or *) CoefficientList[Series[(1 + 5 x - 48 x^2)/((1 - x)^2 (1 - 7 x)), {x, 0, 30}], x]

PROG

(MAGMA) [7^n + 7*n: n in [0..30]]; /* or */ I:=[1, 14, 63]; [n le 3 select I[n] else 9*Self(n-1)-15*Self(n-2)+7*Self(n-3): n in [1..30]];

(PARI) a(n)=7^n+7*n \\ Charles R Greathouse IV, Apr 18 2013

CROSSREFS

Cf. A198397, A176972.

Sequence in context: A050492 A255499 A229739 * A229738 A239856 A214483

Adjacent sequences:  A221906 A221907 A221908 * A221910 A221911 A221912

KEYWORD

nonn,easy

AUTHOR

Vincenzo Librandi, Mar 02 2013

STATUS

approved

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Last modified December 15 14:37 EST 2019. Contains 329999 sequences. (Running on oeis4.)