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A280924
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Numbers k such that 8*10^k + 39 is prime.
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0
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0, 2, 3, 4, 14, 27, 35, 42, 53, 60, 89, 117, 126, 137, 162, 207, 281, 472, 2752, 3381, 6462, 12183, 14910, 29205, 40883, 50675, 78717, 83880, 99113
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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 8 followed by k-2 occurrences of the digit 0 followed by the digits 39 is prime (see Example section).
a(30) > 2*10^5.
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LINKS
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EXAMPLE
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3 is in this sequence because 8*10^3 + 39 = 8039 is prime.
Initial terms and primes associated:
a(1) = 0, 47;
a(2) = 2, 839;
a(3) = 3, 8039;
a(4) = 4, 80039;
a(5) = 14, 800000000000039; etc.
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MATHEMATICA
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Select[Range[0, 100000], PrimeQ[8*10^# + 39] &]
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CROSSREFS
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KEYWORD
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nonn,more,hard
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AUTHOR
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STATUS
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approved
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