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Search: id:A060764
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| A060764 |
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Number of divisors of n which are not also differences between consecutive divisors (ordered by increasing magnitude) of n. |
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+0
3
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| 1, 1, 2, 1, 2, 2, 2, 1, 3, 2, 2, 3, 2, 2, 4, 1, 2, 3, 2, 2, 4, 2, 2, 4, 3, 2, 4, 2, 2, 4, 2, 1, 4, 2, 4, 4, 2, 2, 4, 4, 2, 4, 2, 2, 6, 2, 2, 5, 3, 3, 4, 2, 2, 4, 4, 4, 4, 2, 2, 5, 2, 2, 6, 1, 4, 4, 2, 2, 4, 5, 2, 6, 2, 2, 6, 2, 4, 4, 2, 5, 5, 2, 2, 7, 4, 2, 4, 2, 2, 6, 4, 2, 4, 2, 4, 6, 2, 3, 6, 3, 2, 4, 2, 2, 8
(list; graph; listen)
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OFFSET
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1,3
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EXAMPLE
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For n=70, divisors={1,2,5,7,10,14,35,70}; differences={1,3,2,3,4,21,35}; the divisors {5,7,10,14,70} are not differences, so a(70)=5.
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MATHEMATICA
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a[n_] := Length[Complement[d=Divisors[n], Drop[d, 1]-Drop[d, -1]]]
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CROSSREFS
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Cf. A000005, A060741, A060763.
Sequence in context: A035164 A023588 A001227 this_sequence A105149 A068307 A158946
Adjacent sequences: A060761 A060762 A060763 this_sequence A060765 A060766 A060767
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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 24 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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