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Search: id:A067003
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| A067003 |
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Number of numbers <= n with same number of distinct prime factors as n. |
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+0
3
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| 1, 1, 2, 3, 4, 1, 5, 6, 7, 2, 8, 3, 9, 4, 5, 10, 11, 6, 12, 7, 8, 9, 13, 10, 14, 11, 15, 12, 16, 1, 17, 18, 13, 14, 15, 16, 19, 17, 18, 19, 20, 2, 21, 20, 21, 22, 22, 23, 23, 24, 25, 26, 24, 27, 28, 29, 30, 31, 25, 3, 26, 32, 33, 27, 34, 4, 28, 35, 36, 5, 29, 37, 30, 38, 39, 40, 41
(list; graph; listen)
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OFFSET
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1,3
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FORMULA
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a(A002110(n))=1.
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EXAMPLE
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a(11)=8 since 2,3,4,5,7,8,9,11 each have one distinct prime factor. a(12)=3 since 6,10,12 each have two distinct prime factors.
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CROSSREFS
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Cf. A001221, A008479, A058933, A067004. Inverse of A000961, A007774, A033992, A033993, A051270 etc.
Sequence in context: A133108 A055441 A104717 this_sequence A117386 A101174 A050144
Adjacent sequences: A067000 A067001 A067002 this_sequence A067004 A067005 A067006
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KEYWORD
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nonn
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AUTHOR
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Henry Bottomley (se16(AT)btinternet.com), Dec 21 2001
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