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A294911
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Numbers k such that (299*10^k + 1)/3 is prime.
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0
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1, 2, 3, 5, 6, 8, 11, 12, 36, 63, 79, 152, 159, 236, 365, 542, 734, 2552, 9407, 31832, 32028, 43217, 51139, 58893, 71963, 190533, 197426, 278546
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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 digits 99 followed by k-1 occurrences of the digit 6 followed by the digit 7 is prime (see Example section).
a(29) > 3*10^5.
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LINKS
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EXAMPLE
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2 is in this sequence because (299*10^2 + 1)/3 = 9967 is prime.
Initial terms and associated primes:
a(1) = 1, 997;
a(2) = 2, 9967;
a(3) = 3, 99667;
a(4) = 5, 9966667;
a(5) = 6, 99666667; etc.
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MATHEMATICA
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Select[Range[0, 100000], PrimeQ[(299*10^# + 1)/3] &]
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CROSSREFS
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KEYWORD
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nonn,more,hard,changed
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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