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A327630
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a(n) is the least integer k such that sigma(sigma(k)) >= n*k where sigma is A000203, the sum of divisors.
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1
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1, 2, 6, 6, 24, 24, 24, 60, 120, 480, 540, 1560, 2520, 10920, 27720, 30240, 191520, 360360, 360360, 3243240, 5765760, 28828800, 109549440, 438197760, 766846080, 3834230400, 9081072000, 32974381440, 147516969600, 880887047040, 2802822422400
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OFFSET
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1,2
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COMMENTS
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a(32) <= 14814918518400,
a(33) <= 64464915715200,
a(34) <= 709114072867200,
a(35) <= 9881550651772800,
a(36) <= 76648784785372800,
a(37) <= 2376112328346556800. (End)
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LINKS
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PROG
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(PARI) a(n) = my(k=1); while (sigma(sigma(k))/k < n, k++); k;
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CROSSREFS
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KEYWORD
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nonn,more
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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