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A199564
6*9^n+1.
2
7, 55, 487, 4375, 39367, 354295, 3188647, 28697815, 258280327, 2324522935, 20920706407, 188286357655, 1694577218887, 15251194969975, 137260754729767, 1235346792567895, 11118121133111047, 100063090197999415, 900567811781994727
OFFSET
0,1
FORMULA
a(n) = 9*a(n-1)-8.
a(n) = 10*a(n-1)-9*a(n-2).
G.f.: (7-15*x)/((1-x)*(1-9*x)).
MATHEMATICA
6*9^Range[0, 20]+1 (* or *) LinearRecurrence[{10, -9}, {7, 55}, 20] (* Harvey P. Dale, Apr 16 2014 *)
PROG
(Magma) [6*9^n+1: n in [0..30]];
CROSSREFS
Sequence in context: A108628 A116862 A096307 * A225032 A124403 A005012
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Nov 08 2011
STATUS
approved