A155660 9^n-7^n+1.

1, 3, 33, 387, 4161, 42243, 413793, 3959427, 37281921, 347066883, 3204309153, 29403732867, 268588249281, 2444976817923, 22198569382113, 201143570584707, 1819787258282241, 16444551185679363, 148466221699088673

Offset

0,2

Links

Table of n, a(n) for n=0..18.

Index entries for linear recurrences with constant coefficients, signature (17,-79,63).

Formula

G.f.: 1/(1-9*x)-1/(1-7*x)+1/(1-x). E.g.f.: e^(9*x)-e^(7*x)+e^x.

a(n)=16*a(n-1)-63*a(n-2)+48 with a(0)=1, a(1)=3 - Vincenzo Librandi, Jul 21 2010

Mathematica

LinearRecurrence[{17, -79, 63}, {1, 3, 33}, 30] (* Harvey P. Dale, Feb 25 2015 *)

Prog

(PARI) a(n)=9^n-7^n+1 \\ Charles R Greathouse IV, Jun 11 2015

Crossrefs

Cf. A155638, A155639, A155640, A155641, A155642, A155643, A155644, A155645, A155646, A155647, A155648, A155649, A155650, A155651, A155652, A155653, A155654, A155655, A155656, A155657, A155658, A155659.

Sequence in context: A082778 A228002 A163476 * A299507 A294167 A009502

Adjacent sequences: A155657 A155658 A155659 * A155661 A155662 A155663

Keyword

nonn,easy

Author

Mohammad K. Azarian, Jan 31 2009

Status

approved