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A093675
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Primes of the form 7*10^k + 3*R_k, where R_k is the repunit (A002275) of length k.
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2
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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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Select[Table[FromDigits[PadRight[{7}, n, 3]], {n, 500}], PrimeQ] (* Harvey P. Dale, Nov 11 2014 *)
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PROG
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(Magma) [a: n in [0..200] | IsPrime(a) where a is (22*10^n-1) div 3 ]; // Vincenzo Librandi, May 08 2019
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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