A182923 a(n) = n$ / A055773(n), where n$ denotes the swinging factorial (A056040).
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
Offset: 0
Keywords
Programs
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Maple
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
sf[n_] := n!/Floor[n/2]!^2; a[n_] := sf[n]/Numerator[n!/Floor[n/2]!^4]; Table[a[n], {n, 0, 42}] (* Jean-François Alcover, Jun 22 2019 *)
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