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Search: id:A060765
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| A060765 |
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Numbers n such that every difference between consecutive divisors (ordered by increasing magnitude) of n is also a divisor of n. |
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+0
2
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| 1, 2, 4, 6, 8, 12, 16, 18, 20, 24, 32, 36, 42, 48, 54, 60, 64, 72, 96, 100, 108, 120, 128, 144, 156, 162, 168, 180, 192, 216, 240, 256, 272, 288, 294, 300, 324, 342, 360, 384, 432, 480, 486, 500, 504, 512, 576, 600, 648, 720, 768, 840, 900, 960, 972, 1008, 1024
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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Equivalently, A060763(n)=0. Powers of 2 and factorials up to 7! are here.
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EXAMPLE
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For n = 12, divisors={1, 2, 3, 4, 6, 12}; differences={1, 1, 1, 2, 6}; every difference is a divisor, so 12 is in the sequence.
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MATHEMATICA
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test[n_ ] := Length[Complement[Drop[d=Divisors[n], 1]-Drop[d, -1], d]]==0; Select[Range[1, 1024], test]
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CROSSREFS
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Cf. A060683, A060763.
Sequence in context: A124240 A068997 A067712 this_sequence A140110 A128397 A120383
Adjacent sequences: A060762 A060763 A060764 this_sequence A060766 A060767 A060768
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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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