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A155647
a(n) = 9^n+6^n-1^n.
21
1, 14, 116, 944, 7856, 66824, 578096, 5062904, 44726336, 397498184, 3547250576, 31743856664, 284606318816, 2554926522344, 22955156619056, 206361317079224, 1855841298759296, 16694108359111304, 150196195253667536
OFFSET
0,2
FORMULA
G.f.: 1/(1-9*x)+1/(1-6*x)-1/(1-x). E.g.f.: e^(9*x)+e^(6*x)-e^x.
a(n) = 15*a(n-1)-54*a(n-2)-40 with a(0)=1, a(1)=14. - Vincenzo Librandi, Jul 21 2010
a(0)=1, a(1)=14, a(2)=116, a(n) = 16*a(n-1)-69*a(n-2)+54*a(n-3). - Harvey P. Dale, Dec 04 2012
MATHEMATICA
Table[9^n+6^n-1, {n, 0, 30}] (* or *) LinearRecurrence[{16, -69, 54}, {1, 14, 116}, 30] (* Harvey P. Dale, Dec 04 2012 *)
PROG
(PARI) a(n)=9^n+6^n-1 \\ Charles R Greathouse IV, Sep 24 2015
KEYWORD
nonn,easy
AUTHOR
Mohammad K. Azarian, Jan 31 2009
STATUS
approved