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A020470
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Primes that contain digits 7 and 8 only.
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6
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7, 787, 877, 887, 7877, 8887, 78787, 78877, 78887, 87877, 87887, 777787, 777877, 778777, 787777, 878777, 888887, 7778777, 7788787, 7877777, 7878877, 7878887, 7888877, 8787887, 8788777, 8877787, 8887777, 77778887, 77787887, 77877887
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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[{7, 8}, n], PrimeQ], {n, 8}]] (* Vincenzo Librandi, Jul 28 2012 *)
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PROG
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(Magma) [p: p in PrimesUpTo(77877887) | Set(Intseq(p)) subset [7, 8]]; // Vincenzo Librandi, Jul 28 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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