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A193987
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Least number k such that tau(tau(k)) = n.
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2
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1, 2, 6, 12, 120, 60, 7560, 360, 1260, 2520, 294053760, 5040, 128501493120, 332640, 110880, 55440, 106858629141264000, 277200, 188391763176048432000, 720720, 21621600, 27935107200, 1356699703068812438127792000, 3603600, 857656800, 18632716502400, 6983776800, 183783600
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OFFSET
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1,2
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COMMENTS
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Here tau is the number of divisors function, A000005. Such a k always exists because an upper bound is 2^(2^n-1). For n < 19, and small composite numbers, terms can be found among the highly composite numbers, A002182. The b-file in A005179 is useful when tau^(-1)(n) is small.
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LINKS
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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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