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A293276
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Numbers k such that (74*10^k + 133)/9 is prime.
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0
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0, 1, 3, 4, 7, 10, 19, 24, 27, 85, 93, 99, 133, 292, 309, 676, 894, 2076, 2236, 10968, 20628, 29521, 49054, 57763, 139723, 150616
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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 8 followed by k-2 occurrences of the digit 2 followed by the digits 37 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 (74*10^3 + 133)/9 = 8237 is prime.
Initial terms and primes associated:
a(1) = 0, 23;
a(2) = 1, 97;
a(3) = 3, 8237;
a(4) = 4, 82237;
a(5) = 7, 82222237; etc.
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MATHEMATICA
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Select[Range[0, 100000], PrimeQ[(74*10^# + 133)/9] &]
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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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