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A017558
a(n) = (12*n + 3)^2.
1
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
0,1
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
MATHEMATICA
(12*Range[0, 30]+3)^2 (* or *) LinearRecurrence[{3, -3, 1}, {9, 225, 729}, 30] (* Harvey P. Dale, Aug 04 2015 *)
PROG
(PARI) a(n)=(12*n+3)^2 \\ Charles R Greathouse IV, Jun 17 2017
CROSSREFS
Sequence in context: A120319 A057530 A014736 * A159939 A167038 A074190
KEYWORD
nonn,easy
STATUS
approved