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A000775
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a(n) = n! * (n + 1 + 2*Sum_{k=1...n} 1/k).
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1
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1, 4, 12, 46, 220, 1268, 8568, 66456, 582048, 5681952, 61174080, 720089280, 9199906560, 126783809280, 1874605662720, 29601115891200, 497155992883200, 8849184886886400, 166399076525875200, 3296032301811916800, 68596838245232640000, 1496490349337948160000
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OFFSET
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0,2
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LINKS
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FORMULA
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a(0)=1, a(n+1) = (n+1)*a(n) + (n+3)*n! for n > 0. - Sean A. Irvine, Jun 10 2011
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MATHEMATICA
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Table[n! (n + 1 + 2*Sum[1/k, {k, n}]), {n, 0, 20}] (* T. D. Noe, Jun 20 2012 *)
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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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