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A017198
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a(n) = (9*n + 3)^2.
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4
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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
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OFFSET
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0,1
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COMMENTS
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LINKS
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FORMULA
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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
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MATHEMATICA
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(9*Range[0, 30] + 3)^2 (* or *) LinearRecurrence[{3, -3, 1}, {9, 144, 441}, 30] (* Harvey P. Dale, Dec 25 2015 *)
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PROG
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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