A155669 10^n+9^n-1.

1, 18, 180, 1728, 16560, 159048, 1531440, 14782968, 143046720, 1387420488, 13486784400, 131381059608, 1282429536480, 12541865828328, 122876792454960, 1205891132094648, 11853020188851840, 116677181699666568

Offset

0,2

Links

Table of n, a(n) for n=0..17.

Index entries for linear recurrences with constant coefficients, signature (20,-109,90).

Formula

G.f.: 1/(1-10*x)+1/(1-9*x)-1/(1-x). E.g.f.: e^(10*x)+e^(9*x)-e^x.

a(n)=19*a(n-1)-90*a(n-2)-72 with a(0)=1, a(1)=18 - Vincenzo Librandi, Jul 21 2010

Prog

(PARI) a(n)=10^n+9^n-1 \\ Charles R Greathouse IV, Jun 11 2015

Crossrefs

Cf. A155646, A155647, A155648, A155649, A155650, A155651, A155652, A155653, A155654, A155655, A155656, A155657, A155658, A155659, A155660, A155661, A155662, A155663, A155664, A155665, A155666, A155667, A155668.

Sequence in context: A004410 A140325 A199299 * A160954 A160955 A026091

Adjacent sequences: A155666 A155667 A155668 * A155670 A155671 A155672

Keyword

nonn,easy

Author

Mohammad K. Azarian, Feb 01 2009

Status

approved