A013720 a(n) = 15^(2*n + 1).

15, 3375, 759375, 170859375, 38443359375, 8649755859375, 1946195068359375, 437893890380859375, 98526125335693359375, 22168378200531005859375, 4987885095119476318359375, 1122274146401882171630859375

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn
• easy

Links

• Vincenzo Librandi, Table of n, a(n) for n = 0..200
• Tanya Khovanova, Recursive Sequences
• Index entries for linear recurrences with constant coefficients, signature (225).

Crossrefs

Bisection of A001024 (15^n).

Programs

Magma

[15^(2*n+1): n in [0..15]]; // Vincenzo Librandi, Jun 26 2011

Maple

seq(15^(2*n+1),n=0..11); # Nathaniel Johnston, Jun 25 2011

Mathematica

15^(2Range[0,12]+1)  (* Harvey P. Dale, Feb 09 2011 *)

PARI

a(n)=15^(2*n+1) \\ Charles R Greathouse IV, Jul 11 2016

Formula

From Philippe Deléham, Nov 25 2008: (Start)

a(n) = 225*a(n-1), a(0)=15.

G.f.: 15/(1-225*x). (End)