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A198699
7*10^n-1
1
6, 69, 699, 6999, 69999, 699999, 6999999, 69999999, 699999999, 6999999999, 69999999999, 699999999999, 6999999999999, 69999999999999, 699999999999999, 6999999999999999, 69999999999999999, 699999999999999999
OFFSET
0,1
FORMULA
a(n) = 10*a(n-1)+9. a(n) = 11*a(n-1)-10*a(n-2), n>1.
G.f. ( 6+3*x ) / ( (10*x-1)*(x-1) ). - R. J. Mathar, Oct 29 2011
MATHEMATICA
NestList[10#+9&, 6, 20] (* or *) LinearRecurrence[{11, -10}, {6, 69}, 20] (* Harvey P. Dale, Dec 29 2013 *)
PROG
(Magma) [7*10^n-1: n in [0..30]]
CROSSREFS
Sequence in context: A296016 A288719 A201535 * A346938 A258792 A214694
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Oct 29 2011
STATUS
approved