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A123476
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a(n) = (n!)^2/phi(n!), where phi is Euler's totient function.
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2
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1, 4, 18, 72, 450, 2700, 22050, 176400, 1587600, 15876000, 192099600, 2305195200, 32464832400, 454507653600, 6817614804000, 109081836864000, 1970290678356000, 35465232210408000, 711274934886516000
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OFFSET
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1,2
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COMMENTS
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a(n) is a solution to the equation phi(x) = n!.
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LINKS
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P. Erdos and J. Lambek, Problem 4221, Amer. Math. Monthly, 55 (1948), 103.
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MATHEMATICA
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PROG
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CROSSREFS
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Cf. A055487 (least m such that phi(m) = n!).
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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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