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A046707
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a(n) = n!*Sum_{k=0..n/2} n^(2k)/(2k)!.
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1
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1, 1, 6, 33, 472, 4745, 99216, 1456273, 39669120, 769528593, 25737068800, 622548099041, 24632715009024, 715109889035737, 32630102257170432, 1106618435304908625, 57151019891266256896, 2219208490411286184737, 127876294410780326952960
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OFFSET
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0,3
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LINKS
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MATHEMATICA
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Join[{1}, Table[(n)! Sum[n^(2 k) / (2 k)!, {k, 0, n/2}], {n, 20}]] (* Vincenzo Librandi, Apr 08 2020 *)
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PROG
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(PARI) a(n) = {n!*sum(k=0, n\2, n^(2*k)/(2*k)!)} \\ Andrew Howroyd, Mar 07 2020
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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