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A319068
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a(n) is the greatest k such that A000203(k) divides n where A000203 is the sum of divisors of n.
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2
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1, 1, 2, 3, 1, 5, 4, 7, 2, 1, 1, 11, 9, 13, 8, 7, 1, 17, 1, 19, 4, 1, 1, 23, 1, 9, 2, 13, 1, 29, 25, 31, 2, 1, 4, 22, 1, 37, 18, 27, 1, 41, 1, 43, 8, 1, 1, 47, 4, 1, 2, 9, 1, 53, 1, 39, 49, 1, 1, 59, 1, 61, 32, 31, 9, 5, 1, 67, 2, 13, 1, 71, 1, 73, 8, 37, 4, 45, 1, 79
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OFFSET
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1,3
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COMMENTS
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Sándor names this function the sum-of-divisors maximum function and remarks that this function is well-defined, since a(n) can be at least 1, and cannot be greater than n.
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LINKS
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FORMULA
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a(p+1) = p, for p prime. See Sándor Theorem 2 p. 4.
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PROG
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(PARI) a(n) = {forstep (k=n, 1, -1, if ((n % sigma(k)) == 0, return (k)); ); }
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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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