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A102939
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Numbers k such that 10^k + 6*R_k - 3 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
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2
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1, 2, 3, 18, 177, 324, 388, 392, 404, 531, 1083, 12546, 22443, 54388, 72916, 185520
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OFFSET
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1,2
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COMMENTS
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Also numbers k such that (5*10^k - 11)/3 is prime.
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LINKS
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FORMULA
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MAPLE
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MATHEMATICA
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Do[ If[ PrimeQ[(5*10^n - 11)/3], Print[n]], {n, 0, 10000}]
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CROSSREFS
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KEYWORD
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more,nonn
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AUTHOR
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EXTENSIONS
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Addition of a(12)-a(13) from Kamada data by Robert Price, Dec 12 2010
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STATUS
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approved
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