A064755 a(n) = n*9^n - 1.

8, 161, 2186, 26243, 295244, 3188645, 33480782, 344373767, 3486784400, 34867844009, 345191655698, 3389154437771, 33044255768276, 320275094369453, 3088366981419734, 29648323021629455, 283512088894331672, 2701703435345984177

Offset

1,1

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Paul Leyland, Factors of Cullen and Woodall numbers

Paul Leyland, Generalized Cullen and Woodall numbers

Index entries for linear recurrences with constant coefficients, signature (19, -99, 81).

Formula

From Chai Wah Wu, Feb 01 2018: (Start)

a(n) = 19*a(n-1) - 99*a(n-2) + 81*a(n-3) for n > 3.

G.f.: x*(81*x^2 - 9*x - 8)/((x - 1)*(9*x - 1)^2). (End)

Mathematica

Table[n*9^n-1, {n, 20}] (* Harvey P. Dale, Feb 28 2017 *)

Prog

(Magma) [ n*9^n-1: n in [1..20]]; // Vincenzo Librandi, Sep 16 2011

Crossrefs

Sequence in context: A300466 A184605 A195607 * A140337 A245322 A305524

Adjacent sequences: A064752 A064753 A064754 * A064756 A064757 A064758

Keyword

nonn,easy

Author

N. J. A. Sloane, Oct 19 2001

Status

approved