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A331959
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a(n) is the greatest prime number of the form floor(n/k) where k > 0.
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2
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2, 3, 2, 5, 3, 7, 2, 3, 5, 11, 3, 13, 7, 7, 5, 17, 3, 19, 5, 7, 11, 23, 3, 5, 13, 13, 7, 29, 7, 31, 5, 11, 17, 17, 7, 37, 19, 19, 13, 41, 7, 43, 11, 11, 23, 47, 5, 7, 7, 17, 17, 53, 13, 13, 11, 19, 29, 59, 7, 61, 31, 31, 7, 13, 13, 67, 17, 23, 23, 71, 7, 73
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OFFSET
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2,1
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LINKS
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FORMULA
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a(p) = p for any prime number p.
a(2*p) = p for any prime number p.
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EXAMPLE
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For n = 8:
- floor(8/1) = 8 is not a prime number,
- floor(8/2) = 4 is not a prime number,
- floor(8/3) = 2 is a prime number,
- hence a(8) = 2.
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PROG
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(PARI) a(n) = for (k=1, oo, if (isprime(n\k), return (n\k)))
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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