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A093671
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Primes of the form 10^k + 3*R_k, where R_k is the repunit (A002275) of length k.
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6
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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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Select[Table[FromDigits[PadRight[{1}, n, 3]], {n, 500}], PrimeQ] (* Vincenzo Librandi, Apr 06 2019 *)
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PROG
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(Magma) [a: n in [0..100] | IsPrime(a) where a is ((4*10^n-1) div 3)]; // Vincenzo Librandi, Apr 06 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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