OFFSET
0,1
LINKS
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
KEYWORD
nonn,easy
AUTHOR
STATUS
approved