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A280584
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Numbers k such that (14*10^k - 83)/3 is prime.
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0
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1, 2, 3, 4, 6, 10, 11, 24, 53, 83, 97, 156, 157, 162, 182, 233, 355, 499, 629, 1252, 6378, 8366, 26406, 35345, 107694, 126784, 195234, 255805
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OFFSET
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1,2
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COMMENTS
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For k > 1, numbers k such that the digit 4 followed by k-2 occurrences of the digit 6 followed by the digits 39 is prime (see Example section).
a(29) > 3*10^5.
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LINKS
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EXAMPLE
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4 is in this sequence because (14*10^4 - 83) / 3 = 46639 is prime.
Initial terms and associated primes:
a(1) = 1, 19;
a(2) = 2, 439;
a(3) = 3, 4639;
a(4) = 4, 46639;
a(5) = 6, 4666639; etc.
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MATHEMATICA
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Select[Range[1, 100000], PrimeQ[(14*10^# - 83) / 3] &]
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PROG
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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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EXTENSIONS
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STATUS
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approved
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