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Search: id:A067514
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| A067514 |
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Number of distinct primes of the form floor(n/k) for 1<=k<=n. |
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+0
3
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| 0, 1, 1, 1, 2, 2, 3, 1, 2, 3, 4, 2, 3, 3, 4, 3, 4, 2, 3, 3, 4, 5, 6, 2, 3, 4, 4, 4, 5, 4, 5, 3, 4, 5, 6, 4, 5, 5, 6, 4, 5, 4, 5, 5, 5, 6, 7, 3, 4, 4, 5, 6, 7, 5, 6, 5, 6, 7, 8, 4, 5, 5, 5, 4, 5, 6, 7, 7, 8, 7, 8, 4, 5, 5, 5, 5, 6, 7, 8, 6, 6, 7, 8, 4, 5, 6, 7, 7, 8, 5, 6, 7, 8, 9, 10, 6, 7, 5, 6, 5, 6, 6
(list; graph; listen)
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OFFSET
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1,5
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EXAMPLE
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a(10)=3 as floor(10/k) for k = 1 to 10 is 10,5,3,2,2,1,1,1,1,1, respectively; the 3 primes are 5,3,2.
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MATHEMATICA
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a[n_] := Length[Union[Select[Table[Floor[n/i], {i, 1, n}], PrimeQ]]]
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CROSSREFS
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Cf. A068050.
Sequence in context: A054707 A166269 A055460 this_sequence A115323 A089282 A079688
Adjacent sequences: A067511 A067512 A067513 this_sequence A067515 A067516 A067517
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KEYWORD
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easy,nonn
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AUTHOR
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Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Feb 12 2002
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EXTENSIONS
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Edited by Dean Hickerson (dean.hickerson(AT)yahoo.com), Feb 12 2002
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