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A294231
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Numbers k such that (56*10^k + 367)/9 is prime.
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0
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0, 1, 3, 6, 7, 12, 31, 33, 997, 1134, 3253, 3462, 6154, 9345, 10558, 13251, 15169, 18511, 19219, 22476, 25536, 31399, 35997, 51793, 124735
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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 6 followed by k-2 occurrences of the digit 2 followed by the digits 63 is prime (see Example section).
a(26) > 2*10^5.
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LINKS
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EXAMPLE
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3 is in this sequence because (56*10^3 + 367)/9 = 6263 is prime.
Initial terms and primes associated:
a(1) = 0, 47;
a(2) = 1, 103;
a(3) = 3, 6263;
a(4) = 6, 6222263;
a(5) = 7, 62222263; etc.
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MATHEMATICA
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Select[Range[0, 100000], PrimeQ[(56*10^# + 367)/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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