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A351612
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Number of ordered pairs, (s,t), 1 <= s <= t, such that (t^s) | n.
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0
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1, 2, 2, 4, 2, 4, 2, 5, 4, 4, 2, 7, 2, 4, 4, 7, 2, 7, 2, 7, 4, 4, 2, 9, 4, 4, 6, 7, 2, 8, 2, 8, 4, 4, 4, 12, 2, 4, 4, 9, 2, 8, 2, 7, 7, 4, 2, 12, 4, 7, 4, 7, 2, 10, 4, 9, 4, 4, 2, 13, 2, 4, 7, 11, 4, 8, 2, 7, 4, 8, 2, 15, 2, 4, 7, 7, 4, 8, 2, 12, 8, 4, 2, 13, 4, 4, 4, 9, 2, 13
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OFFSET
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1,2
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LINKS
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FORMULA
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a(n) = Sum_{(t^s)|n, 1<=s<=t<=n} 1.
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EXAMPLE
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a(9) = 4; The ordered pairs are (1,1), (1,3), (1,9), (2,3).
a(36) = 12; The ordered pairs are (1,1), (1,2), (1,3), (1,4), (1,6), (1,9), (1,12), (1,18), (1,36), (2,2), (2,3), (2,6).
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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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