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A020459
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Primes that contain digits 2 and 7 only.
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8
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2, 7, 227, 277, 727, 2777, 7727, 22277, 22727, 22777, 27277, 72227, 72277, 72727, 272227, 272777, 727777, 777277, 2227727, 2227777, 2272727, 2277727, 2727727, 2772227, 7272227, 7722277, 7727777, 7772777, 7777727, 22227277, 22272277
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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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Flatten[Table[Select[FromDigits/@Tuples[{2, 7}, n], PrimeQ], {n, 8}]] (* Vincenzo Librandi, Jul 27 2012 *)
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PROG
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(Magma) [p: p in PrimesUpTo(22272277) | Set(Intseq(p)) subset [2, 7]]; // Vincenzo Librandi, Jul 27 2012
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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STATUS
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approved
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