A199689 a(n) = 8*10^n + 1.

9, 81, 801, 8001, 80001, 800001, 8000001, 80000001, 800000001, 8000000001, 80000000001, 800000000001, 8000000000001, 80000000000001, 800000000000001, 8000000000000001, 80000000000000001, 800000000000000001, 8000000000000000001, 80000000000000000001, 800000000000000000001

Offset

0,1

Links

Vincenzo Librandi, Table of n, a(n) for n = 0..1000

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

Formula

a(n) = 9*A059482(n).

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

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

G.f.: 9*(1-2*x)/((1-x)*(1-10*x)).

From Elmo R. Oliveira, May 04 2025: (Start)

E.g.f.: exp(x)*(1 + 8*exp(9*x)).

a(n) = 3*A199688(n). (End)

Mathematica

8*10^Range[0, 20]+1 (* or *) LinearRecurrence[{11, -10}, {9, 81}, 20] (* Harvey P. Dale, Jun 11 2022 *)

Prog

(Magma) [8*10^n+1: n in [0..30]];

Crossrefs

Cf. A059482, A199688.

Sequence in context: A144821 A344253 A338727 * A181581 A137062 A001514

Adjacent sequences: A199686 A199687 A199688 * A199690 A199691 A199692

Keyword

nonn,easy

Author

Vincenzo Librandi, Nov 09 2011

Status

approved