A017630 a(n) = (12*n+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, 127449, 136161, 145161, 154449, 164025, 173889, 184041, 194481
Offset: 0
Links
- Index entries for linear recurrences with constant coefficients, signature (3,-3,1).
Programs
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Mathematica
(12*Range[0,40]+9)^2 (* or *) LinearRecurrence[{3,-3,1},{81,441,1089},40] (* Harvey P. Dale, Mar 31 2012 *) -
PARI
a(n)=(12*n+9)^2 \\ Charles R Greathouse IV, Jun 17 2017
Formula
From Harvey P. Dale, Mar 31 2012: (Start)
a(0)=81, a(1)=441, a(2)=1089, a(n) = 3*a(n-1)-3*a(n-2)+a(n-3).
G.f.: -9*(x^2+22*x+9)/(x-1)^3. (End)
a(n) = 9*A016838(n). - R. J. Mathar, Mar 21 2016
Extensions
More terms from Jason Yuen, Sep 01 2025