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A096225
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a(0) = 1; for n >= 0, a(n+1) = smallest prime factor of a(n)! + 1.
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2
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OFFSET
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0,2
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LINKS
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EXAMPLE
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71!+1 is the product of 6653 and a large prime.
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MATHEMATICA
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a[1] = 2; a[n_] := Block[{p = PrimePi[a[n - 1]] + 1, r = a[n - 1]! + 1}, While[ Mod[r, Prime[p]] != 0, p++ ]; Prime[p]]; Do[ Print[ a[n]], {n, 7}] (* Robert G. Wilson v, Aug 12 2004 *)
NestList[FactorInteger[#!+1][[1, 1]]&, 1, 7] (* Harvey P. Dale, Sep 20 2016 *)
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CROSSREFS
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KEYWORD
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nonn,more,hard,nice
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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