A118004 a(n) = 9^n - 4^n.

0, 5, 65, 665, 6305, 58025, 527345, 4766585, 42981185, 387158345, 3485735825, 31376865305, 282412759265, 2541798719465, 22876524019505, 205890058352825, 1853015893884545, 16677164519797385, 150094566577522385

Offset

0,2

Links

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

Eric Weisstein's World of Mathematics, Cantor Square Fractal

Index entries for linear recurrences with constant coefficients, signature (13,-36)

Formula

a(n) = 5*A016153(n).

a(n) = 13*a(n-1) - 36*a(n-2), n>=2. - Vincenzo Librandi, Mar 16 2011

G.f.: 5*x / ( (9*x-1)*(4*x-1) ). - R. J. Mathar, Mar 18 2011

Mathematica

Table[9^n-4^n, {n, 0, 20}] (* or *) LinearRecurrence[{13, -36}, {0, 5}, 20] (* Harvey P. Dale, May 11 2017 *)

Prog

(PARI) a(n)=9^n-4^n \\ Charles R Greathouse IV, Oct 07 2015

Crossrefs

Cf. A016153.

Sequence in context: A195579 A296369 A061184 * A281232 A236321 A199024

Adjacent sequences: A118001 A118002 A118003 * A118005 A118006 A118007

Keyword

nonn,easy

Author

Eric W. Weisstein, Apr 09 2006

Status

approved