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A240160
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Least number k such that (k!-n)/k is prime, or 0 if no such k exists.
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2
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0, 0, 0, 4, 5, 0, 7, 8, 0, 0, 0, 4, 13, 0, 15, 4, 0, 0, 0, 0, 0, 0, 0, 0, 5, 0, 0, 0, 0, 0, 31, 0, 33, 34, 5, 0, 0, 0, 39, 0, 0, 6, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 5, 0, 0, 0, 0, 0, 0, 0, 0, 0, 5, 6, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 7, 6, 0, 0, 0, 0, 0, 0, 5, 0, 0, 0, 0, 0, 0, 0, 0, 0, 5
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OFFSET
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1,4
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COMMENTS
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For a(n) > 0, a(n) is a divisor of n.
If a(n) = n, then n - 1 is in A002982.
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LINKS
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PROG
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(PARI)
a(n)=for(k=1, n, s=(k!-n)/k; if(floor(s)==s, if(ispseudoprime(s), return(k))))
vector(150, n, a(n))
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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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