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A276672
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Numbers k such that (19*10^k + 101) / 3 is prime.
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0
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1, 3, 4, 9, 10, 12, 13, 16, 20, 37, 57, 66, 106, 116, 127, 355, 396, 547, 2289, 3777, 4500, 7821, 15663, 22746, 25978, 30434, 39682, 119716, 133390, 145093, 200260
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OFFSET
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1,2
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COMMENTS
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For k>1, numbers such that the digit 6 followed by k-2 occurrences of the digit 3 followed by the digits 67 is prime (see Example section).
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LINKS
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EXAMPLE
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3 is in this sequence because (19*10^3 + 101) / 3 = 6367 is prime.
Initial terms and primes associated:
a(1) = 1, 97;
a(2) = 3, 6367;
a(3) = 4, 63367;
a(4) = 9, 6333333367;
a(5) = 10, 63333333367, etc.
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MATHEMATICA
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Select[Range[0, 100000], PrimeQ[(19*10^# + 101) / 3] &]
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PROG
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(Magma) [n: n in [0..400] |IsPrime((19*10^n + 101) div 3)]; // Vincenzo Librandi, Sep 13 2016
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CROSSREFS
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KEYWORD
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nonn,more
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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