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A060683
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Numbers for which the differences between consecutive divisors (ordered by size) are distinct.
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3
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1, 2, 3, 4, 5, 7, 8, 9, 10, 11, 13, 14, 16, 17, 19, 21, 22, 23, 25, 26, 27, 28, 29, 31, 32, 33, 34, 35, 37, 38, 39, 41, 43, 44, 46, 47, 49, 50, 51, 52, 53, 55, 57, 58, 59, 61, 62, 64, 65, 67, 68, 69, 71, 73, 74, 76, 77, 79, 81, 82, 83, 85, 86, 87, 88, 89, 92, 93, 94, 95, 97, 98
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history;
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OFFSET
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1,2
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REFERENCES
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A. Balog, P. Erdos and G. Tenenbaum, On Arithmetic Functions Involving Consecutive Divisors. In: Analytical Number Theory, pp. 77-90, Birkhauser, Basel, 1990.
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LINKS
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Table of n, a(n) for n=1..72.
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EXAMPLE
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For n=6, divisors={1,2,3,6}; differences={1,1,3}, which are not distinct, so 6 is not in the sequence.
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MATHEMATICA
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test[n_ ] := Length[dd=Drop[d=Divisors[n], 1]-Drop[d, -1]]==Length[Union[dd]]; Select[Range[1, 100], test]
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CROSSREFS
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Cf. A000005, A060680-A060682, A060765.
Sequence in context: A153381 A091010 A116358 * A129511 A174905 A191849
Adjacent sequences: A060680 A060681 A060682 * A060684 A060685 A060686
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KEYWORD
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nonn
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AUTHOR
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Labos E. (labos(AT)ana.sote.hu), Apr 19 2001
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EXTENSIONS
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Edited by Dean Hickerson (dean.hickerson(AT)yahoo.com), Jan 22 2002
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STATUS
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approved
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