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A208124
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a(1)=2, a(n) = (4n/3)*(2n-1)!! (see A001147) for n>1.
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0
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2, 8, 60, 560, 6300, 83160, 1261260, 21621600, 413513100, 8729721000, 201656555100, 5059746291600, 137034795397500, 3984550204635000, 123805667072587500, 4093840724533560000, 143540290403957947500, 5319434291440794525000, 207753461493493252837500, 8528826313943407221750000
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OFFSET
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1,1
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LINKS
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FORMULA
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(n-1)*a(n) =n*(2n-1)*a(n-1), n>2. - R. J. Mathar, Mar 27 2012
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MATHEMATICA
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a[n_] := If[n == 1, 2, (4n/3)*(2n - 1)!!]; Array[a, 20] (* Amiram Eldar, Dec 01 2018 *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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