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A295522
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Numbers k such that (16*10^k + 107)/3 is prime.
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0
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0, 1, 2, 8, 18, 24, 96, 152, 204, 296, 566, 703, 1814, 4342, 4626, 5412, 6704, 6752, 7096, 27004, 37976, 173251
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OFFSET
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1,3
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COMMENTS
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For k > 1, numbers such that the digit 5 followed by k-2 occurrences of the digit 3 followed by the digits 69 is prime (see Example section).
a(23) > 2*10^5.
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LINKS
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EXAMPLE
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2 is in this sequence because (16*10^2 + 107)/3 = 569 is prime.
Initial terms and primes associated:
a(1) = 0, 41;
a(2) = 1, 89;
a(3) = 2, 569;
a(4) = 8, 533333369;
a(5) = 18, 5333333333333333369; etc.
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MATHEMATICA
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Select[Range[0, 100000], PrimeQ[(16*10^# + 107)/3] &]
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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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