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A181858
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a(n) = lcm(n^2, n!) / lcm(n^2, swinging_factorial(n)).
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1
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1, 1, 1, 1, 1, 4, 4, 36, 18, 64, 576, 14400, 43200, 518400, 518400, 5080320, 12700800, 1625702400, 1625702400, 131681894400, 131681894400, 627056640000, 13168189440000, 1593350922240000
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OFFSET
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0,6
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COMMENTS
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A divisibility sequence, i.e., if m|n then a(m)|a(n). Except for n = 9 the prime factors of A181858(n) are the primes <= floor((n-1)/2). Using this fact the divisibility property can be proved. - Peter Luschny, Jan 10 2011
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LINKS
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FORMULA
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MAPLE
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A181858 := n -> `if`(n=0, 1, ilcm(n^2, n!)/ilcm(n^2, n!/iquo(n, 2)!^2));
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MATHEMATICA
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a[n_] := If[n == 0, 1, LCM[n^2, n!]/LCM[n^2, n!/Quotient[n, 2]!^2]];
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PROG
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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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