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A182923
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a(n) = n$ / A055773(n), where n$ denotes the swinging factorial (A056040).
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1
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1, 1, 1, 1, 2, 2, 4, 4, 2, 18, 36, 36, 12, 12, 24, 360, 90, 90, 20, 20, 4, 84, 168, 168, 28, 700, 1400, 37800, 5400, 5400, 720, 720, 90, 2970, 5940, 207900, 23100, 23100, 46200, 1801800, 180180, 180180, 17160
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OFFSET
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0,5
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COMMENTS
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a(n) = n$ * P(floor(n/2))/P(n), P(n) primorial number A034386.
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LINKS
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MAPLE
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swingfact := n -> n! / iquo(n, 2)!^2;
A182923 := n -> swingfact(n) / mul(k, k=select(isprime, [$iquo(n, 2)+1..n])):
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MATHEMATICA
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sf[n_] := n!/Floor[n/2]!^2;
a[n_] := sf[n]/Numerator[n!/Floor[n/2]!^4];
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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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