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A139205
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Numbers k such that (k!-10)/10 is prime.
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20
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5, 6, 7, 11, 13, 17, 28, 81, 87, 433, 640, 647, 798, 1026, 1216, 1277, 3825, 6684
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OFFSET
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1,1
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COMMENTS
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LINKS
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MATHEMATICA
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a = {}; Do[If[PrimeQ[(n! - 10)/10], Print[a]; AppendTo[a, n]], {n, 1, 300}]; a (*Artur Jasinski*)
Select[Range[700], PrimeQ[(#!-10)/10]&] (* Harvey P. Dale, Feb 15 2015 *)
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CROSSREFS
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Cf. n!/m-1 is a prime: A002982, A082671, A139056, A139199-A139205; n!/m+1 is a prime: A002981, A082672, A089085, A139061, A139058, A139063, A139065, A151913, A137390, A139071 (1<=m<=10).
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KEYWORD
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hard,more,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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