A017198 a(n) = (9*n + 3)^2.

9, 144, 441, 900, 1521, 2304, 3249, 4356, 5625, 7056, 8649, 10404, 12321, 14400, 16641, 19044, 21609, 24336, 27225, 30276, 33489, 36864, 40401, 44100, 47961, 51984, 56169, 60516, 65025, 69696

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn
• easy

Comments

a(n) = A000290(A017197(n)) = A156677(n+2) + A017305(n). - Reinhard Zumkeller, Jul 13 2010

Links

• Vincenzo Librandi, Table of n, a(n) for n = 0..10000
• Index entries for linear recurrences with constant coefficients, signature (3,-3,1).

Programs

Magma

[(9*n+3)^2: n in [0..35]]; // Vincenzo Librandi, Jul 23 2011

Mathematica

(9*Range[0, 30] + 3)^2 (* or *) LinearRecurrence[{3,-3,1},{9,144,441},30] (* Harvey P. Dale, Dec 25 2015 *)

PARI

a(n)=(9*n+3)^2 \\ Charles R Greathouse IV, Jun 17 2017

Formula

a(0)=9, a(1)=144, a(2)=441, a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3). - Harvey P. Dale, Dec 25 2015

G.f.: (-9 - 117*x - 36*x^2) / (x-1)^3. - R. J. Mathar, Jul 14 2016