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A129326
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a(n) = (2*n+1)*(n-1)!.
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9
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3, 5, 14, 54, 264, 1560, 10800, 85680, 766080, 7620480, 83462400, 997920000, 12933043200, 180583603200, 2702527027200, 43153254144000, 732297646080000, 13160434839552000, 249692574523392000, 4987449116762112000, 104614786351595520000, 2299092397726924800000
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OFFSET
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1,1
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COMMENTS
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LINKS
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FORMULA
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a(n) = (n+1)!*h(n+1) - n*(n+1)*(n-1)!*h(n-1), where h(n) = Sum_{k=1..n} 1/k. - Gary Detlefs, Jul 19 2011
Sum_{n>=1} 1/a(n) = e/2 - sqrt(Pi)*erfi(1)/4. - Amiram Eldar, Oct 07 2020
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MATHEMATICA
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PROG
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(PARI) vector(30, n, (2*n+1)*(n-1)!) \\ G. C. Greubel, Nov 02 2018
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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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EXTENSIONS
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STATUS
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approved
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