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A276470
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Numbers n such that (25*10^n + 167) / 3 is prime.
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0
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1, 3, 4, 5, 11, 15, 18, 37, 41, 58, 60, 87, 117, 118, 214, 265, 334, 355, 450, 655, 1695, 1734, 2183, 3913, 25313, 32865
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OFFSET
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1,2
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COMMENTS
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For n>1, numbers such that the digit 8 followed by n-2 occurrences of the digit 3 followed by the digits 89 is prime (see Example section).
a(27) > 2*10^5.
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LINKS
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EXAMPLE
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3 is in this sequence because (25*10^3 + 167) / 3 = 8389 is prime.
Initial terms and primes associated:
a(1) = 1, 139;
a(2) = 3, 8389
a(3) = 4, 83389;
a(4) = 5, 833389;
a(5) = 11, 833333333389, etc.
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MATHEMATICA
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Select[Range[0, 100000], PrimeQ[(25*10^# + 167) / 3] &]
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PROG
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(Magma) [n: n in [0..400] |IsPrime((25*10^n + 167) 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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STATUS
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approved
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