A017558 a(n) = (12*n + 3)^2.

9, 225, 729, 1521, 2601, 3969, 5625, 7569, 9801, 12321, 15129, 18225, 21609, 25281, 29241, 33489, 38025, 42849, 47961, 53361, 59049, 65025, 71289, 77841, 84681, 91809, 99225, 106929, 114921, 123201

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn
• easy

Links

• Index entries for linear recurrences with constant coefficients, signature (3,-3,1).

Programs

Mathematica

(12*Range[0,30]+3)^2 (* or *) LinearRecurrence[{3,-3,1},{9,225,729},30] (* Harvey P. Dale, Aug 04 2015 *)

PARI

a(n)=(12*n+3)^2 \\ Charles R Greathouse IV, Jun 17 2017

Formula

G.f.: 9*(1 + 22*x + 9*x^2)/(1-x)^3.

a(n) = 9*A016814(n).

a(n) = a(n-1) + 288*n - 72, n >= 1. - Vincenzo Librandi, Mar 20 2011