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A155663
a(n) = 9^n + 8^n - 1.
12
1, 16, 144, 1240, 10656, 91816, 793584, 6880120, 59823936, 521638216, 4560526224, 39970994200, 351149013216, 3091621642216, 27274838966064, 241075504183480, 2134495165562496, 18928981513351816, 168109033806481104, 1494966905748847960, 13310586963663775776
OFFSET
0,2
FORMULA
G.f.: 1/(1-9*x)+1/(1-8*x)-1/(1-x).
E.g.f.: exp(9*x)+exp(8*x)-exp(x).
a(n) = 17*a(n-1)-72*a(n-2)-56 with a(0) = 1, a(1) = 16. - Vincenzo Librandi, Jul 21 2010
MATHEMATICA
Table[9^n+8^n-1, {n, 0, 20}] (* or *) LinearRecurrence[{18, -89, 72}, {1, 16, 144}, 20] (* Harvey P. Dale, Jun 14 2016 *)
PROG
(PARI) a(n)=9^n+8^n-1 \\ Charles R Greathouse IV, Jun 11 2015
KEYWORD
nonn,easy
AUTHOR
Mohammad K. Azarian, Jan 31 2009
STATUS
approved