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

Author

Mohammad K. Azarian, Feb 01 2009

Keywords

• nonn
• easy

Links

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

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.

Programs

PARI

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

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