A198973 8*10^n-1.

7, 79, 799, 7999, 79999, 799999, 7999999, 79999999, 799999999, 7999999999, 79999999999, 799999999999, 7999999999999, 79999999999999, 799999999999999, 7999999999999999, 79999999999999999, 799999999999999999, 7999999999999999999

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 A372969 A014293

Adjacent sequences: A198970 A198971 A198972 * A198974 A198975 A198976

Keyword

nonn,easy

Author

Vincenzo Librandi, Nov 02 2011

Status

approved