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A198973 8*10^n-1. 1
7, 79, 799, 7999, 79999, 799999, 7999999, 79999999, 799999999, 7999999999, 79999999999, 799999999999, 7999999999999, 79999999999999, 799999999999999, 7999999999999999, 79999999999999999, 799999999999999999, 7999999999999999999 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..200

Index entries for linear recurrences with constant coefficients, signature (11,-10).

FORMULA

a(n) = 10*a(n-1)+9.

a(n) = 11*a(n-1)-10*a(n-2), n>1.

G.f.: (7 + 2*x)/(1 - 11*x + 10*x^2). - Vincenzo Librandi, Jan 04 2013

MATHEMATICA

Table[FromDigits[PadRight[{7}, n, 9]], {n, 20}] (* Harvey P. Dale, Jun 05 2012 *)

CoefficientList[Series[(7 + 2*x)/(1 - 11*x + 10*x^2), {x, 0, 30}], x] (* Vincenzo Librandi, Jan 04 2013 *)

PROG

(MAGMA) [8*10^n-1 : n in [0..20]]

CROSSREFS

Sequence in context: A220382 A036950 A127890 * A127859 A014293 A176792

Adjacent sequences:  A198970 A198971 A198972 * A198974 A198975 A198976

KEYWORD

nonn,easy

AUTHOR

Vincenzo Librandi, Nov 02 2011

STATUS

approved

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Last modified January 23 13:57 EST 2022. Contains 350511 sequences. (Running on oeis4.)