A139747 a(n) = 11^n - 9^n.

0, 2, 40, 602, 8080, 102002, 1240120, 14704202, 171312160, 1970527202, 22450640200, 253930611002, 2855998840240, 31980846315602, 356873041128280, 3971357037321002, 44096709674720320, 488769846799627202, 5409822678195232360, 59808238730741554202, 660592329473503080400

Offset

0,2

Links

Vincenzo Librandi, Table of n, a(n) for n = 0..300

Index entries for linear recurrences with constant coefficients, signature (20,-99).

Formula

a(n) = 20*a(n-1) - 99*a(n-2). - Vincenzo Librandi, Jun 02 2011

From Elmo R. Oliveira, Mar 31 2025: (Start)

G.f.: 2*x/((1-9*x)*(1-11*x)).

E.g.f.: 2*exp(10*x)*sinh(x). (End)

Mathematica

Table[11^n-9^n, {n, 0, 30}] (* or *) LinearRecurrence[{20, -99}, {0, 2}, 30] (* Harvey P. Dale, Apr 10 2016 *)

Prog

(Magma) [11^n-9^n: n in [0..30]]; // Vincenzo Librandi, Jun 02 2011

Crossrefs

Sequence in context: A108033 A160229 A012807 * A230133 A279214 A264716

Adjacent sequences: A139744 A139745 A139746 * A139748 A139749 A139750

Keyword

nonn,easy

Author

N. J. A. Sloane, May 20 2008

Status

approved