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A204841
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(2n)! - 2^n*n!.
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0
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0, 0, 16, 672, 39936, 3624960, 478955520, 87177646080, 20922779566080, 6402373519933440, 2432902004460748800, 1124000727695858073600, 620448401731277448806400, 403291461126554623829606400, 304888344611712432172380979200, 265252859812191015786434789376000
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OFFSET
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0,3
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COMMENTS
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a(n) is the number of ways to seat (linearly order) n married couples so that at least one couple is separated.
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LINKS
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FORMULA
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MATHEMATICA
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Table[(2n)! - 2^n n!, {n, 0, 20}]
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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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