A199679 (11*9^n+1)/4.

3, 25, 223, 2005, 18043, 162385, 1461463, 13153165, 118378483, 1065406345, 9588657103, 86297913925, 776681225323, 6990131027905, 62911179251143, 566200613260285, 5095805519342563, 45862249674083065, 412760247066747583

Offset

0,1

Links

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

Index entries for linear recurrences with constant coefficients, signature (10,-9).

Formula

a(n) = 9*a(n-1)-2.

a(n) = 10*a(n-1)-9*a(n-2).

G.f.: (3-5*x)/((1-x)*(1-9*x)).

Mathematica

(11 9^Range[0, 20]+1)/4 (* or *) LinearRecurrence[{10, -9}, {3, 25}, 20] (* Harvey P. Dale, Apr 29 2019 *)

Prog

(Magma) [(11*9^n+1)/4: n in [0..30]];

Crossrefs

Sequence in context: A155640 A370104 A024217 * A118726 A372458 A066221

Adjacent sequences: A199676 A199677 A199678 * A199680 A199681 A199682

Keyword

nonn,easy

Author

Vincenzo Librandi, Nov 09 2011

Status

approved