A166157 a(n) = (8^n+16*(-9)^n)/17.

1, -8, 80, -656, 6416, -53648, 515600, -4378256, 41501456, -356735888, 3344840720, -29029824656, 269858356496, -2360005731728, 21789807399440, -191710220083856, 1760576352843536, -15563712198881168

Offset

0,2

Links

G. C. Greubel, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (-1, 72).

Formula

a(n) = 72*a(n-2)-a(n-1), a(0)= 1, a(1)= -8, for n>1.

G.f.: (1-7x)/(1+x-72*x^2).

a(n)= Sum_{k, 0<=k<=n} A112555(n,k)*(-9)^k.

E.g.f.: (1/17)*(exp(8*x) + 16*exp(-9*x)). - G. C. Greubel, May 01 2016

Mathematica

LinearRecurrence[{-1, 72}, {1, -8}, 20] (* Harvey P. Dale, Jun 23 2012 *)

Prog

(PARI) a(n)=(8^n+16*(-9)^n)/17 \\ Charles R Greathouse IV, May 02 2016

Crossrefs

Cf. A166035, A166036, A166149, A166152, A166153.

Sequence in context: A100472 A043035 A165760 * A145729 A280121 A182604

Adjacent sequences: A166154 A166155 A166156 * A166158 A166159 A166160

Keyword

easy,sign

Author

Philippe Deléham, Oct 08 2009

Status

approved