A017630 (12n+9)^2.

81, 441, 1089, 2025, 3249, 4761, 6561, 8649, 11025, 13689, 16641, 19881, 23409, 27225, 31329, 35721, 40401, 45369, 50625, 56169, 62001, 68121, 74529, 81225, 88209, 95481, 103041, 110889, 119025

Offset

0,1

Links

Table of n, a(n) for n=0..28.

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

Formula

a(0)=81, a(1)=441, a(2)=1089, a(n)=3*a(n-1)-3*a(n-2)+a(n-3) [From Harvey P. Dale, Mar 31 2012]

G.f.: -9*(x^2+22*x+9)/(x-1)^3. [From Harvey P. Dale, Mar 31 2012]

a(n) = 9*A016838(n). - R. J. Mathar, Mar 21 2016

Mathematica

(12*Range[0, 30]+9)^2 (* or *) LinearRecurrence[{3, -3, 1}, {81, 441, 1089}, 30] (* Harvey P. Dale, Mar 31 2012 *)

Prog

(PARI) a(n)=(12*n+9)^2 \\ Charles R Greathouse IV, Jun 17 2017

Crossrefs

Sequence in context: A237301 A237945 A237938 * A270538 A230064 A236710

Adjacent sequences: A017627 A017628 A017629 * A017631 A017632 A017633

Keyword

nonn,easy

Author

N. J. A. Sloane.

Status

approved