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A129932
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Numbers n such that n remains prime through 6 iterations of function f(x) = 2x + 5.
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1
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541, 1861, 109111, 119101, 131617, 895351, 1774447, 2343037, 2906623, 3686743, 3686953, 4330783, 4594309, 4921129, 4922329, 5495989, 5654137, 6712591, 7093057, 7729537, 9188623, 9842263, 10492297, 10991983, 11270671, 12307453
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OFFSET
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1,1
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LINKS
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MATHEMATICA
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fQ[n_] := Union[PrimeQ /@ NestList[2 # + 5 &, n, 6]] == {True}; lst = {}; Do[ p = Prime@n; If[fQ@p, Print@p; AppendTo[lst, p]], {n, 10^7}]; lst (* Robert G. Wilson v *)
Select[Range[12400000], And@@PrimeQ/@NestList[2#+5&, #, 6]&] (* Harvey P. Dale, Sep 09 2012 *)
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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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