A198970 a(n) = 4*10^n-1.

3, 39, 399, 3999, 39999, 399999, 3999999, 39999999, 399999999, 3999999999, 39999999999, 399999999999, 3999999999999, 39999999999999, 399999999999999, 3999999999999999, 39999999999999999, 399999999999999999, 3999999999999999999

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) = 3*A097166(n).

a(n) = 10*a(n-1)+9, n>0.

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

G.f.: 3*(1 + 2*x)/(1 - 11*x + 10*x^2). - Vincenzo Librandi, Jan 03 2013

Mathematica

CoefficientList[Series[3*(1 + 2*x)/(1 - 11*x + 10*x^2), {x, 0, 30}], x] (* Vincenzo Librandi, Jan 03 2013 *)

Prog

(Magma) [4*10^n-1 : n in [0..20]]

Crossrefs

Sequence in context: A191468 A203243 A063035 * A361539 A014850 A341671

Adjacent sequences: A198967 A198968 A198969 * A198971 A198972 A198973

Keyword

nonn,easy

Author

Vincenzo Librandi, Nov 01 2011

Status

approved