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A072490
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Number of squarefree numbers (excluding 1) less than n.
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1
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0, 0, 1, 2, 2, 3, 4, 5, 5, 5, 6, 7, 7, 8, 9, 10, 10, 11, 11, 12, 12, 13, 14, 15, 15, 15, 16, 16, 16, 17, 18, 19, 19, 20, 21, 22, 22, 23, 24, 25, 25, 26, 27, 28, 28, 28, 29, 30, 30, 30, 30, 31, 31, 32, 32, 33, 33, 34, 35, 36, 36, 37, 38, 38, 38, 39
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OFFSET
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1,4
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LINKS
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FORMULA
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EXAMPLE
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a(10) = 5 as the squarefree numbers less than 10 are 2,3,5,6 and 7.
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PROG
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(PARI) a(n) = sum(k=2, n-1, issquarefree(k)); \\ Michel Marcus, Sep 15 2019
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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