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A092967
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Largest prime of the form a squarefree number + 1 where the prime divisors of the squarefree number are < n.
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2
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2, 3, 7, 7, 31, 31, 211, 211, 211, 211, 2311, 2311, 6007, 6007, 6007, 6007, 102103, 102103, 3233231, 3233231, 3233231, 3233231, 17160991
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OFFSET
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1,1
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COMMENTS
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Conjecture: a(n)-1 has prime(n)-1 divisors. Subsidiary sequence: Number of primes of the form 2*p*q*r*...+1 where p, q, r, etc. are distinct odd primes < n.
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LINKS
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EXAMPLE
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a(13) = 6007 = 2*3*7*11*13 + 1, as 2*5*7*11*13 + 1, etc. are composite.
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MATHEMATICA
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<<DiscreteMath`; <<NumberTheory`; Do[l = Select[Map[Times @@ #&, Subsets[Range[n]]], SquareFreeQ]; Print[Max[Select[Map[ #+1&, l], PrimeQ]]], {n, 1, 30}] (* Ryan Propper, Aug 13 2005 *)
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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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