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A296053
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Numbers k such that (46*10^k + 683)/9 is prime.
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0
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1, 2, 11, 17, 35, 56, 91, 187, 199, 224, 625, 655, 665, 959, 1457, 1501, 1970, 4478, 12514, 45820, 68698, 113969, 117902, 182896, 192841
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OFFSET
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1,2
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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 1 followed by the digits 87 is prime (see Example section).
a(26) > 2*10^5.
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LINKS
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EXAMPLE
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2 is in this sequence because (46*10^2 + 683)/9 = 587 is prime.
Initial terms and primes associated:
a(1) = 1, 127;
a(2) = 2, 587;
a(3) = 11, 511111111187;
a(4) = 17, 511111111111111187;
a(5) = 35, 511111111111111111111111111111111187; etc.
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MATHEMATICA
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Select[Range[0, 100000], PrimeQ[(46*10^# + 683)/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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