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A102999
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Numbers n such that 4*10^n + 8*R_n - 1 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
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1
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0, 1, 2, 7, 14, 25, 116, 427, 595, 637, 776, 1706, 16628, 55558
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OFFSET
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1,3
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COMMENTS
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Also numbers n such that (44*10^n-17)/9 is prime.
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LINKS
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FORMULA
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MATHEMATICA
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Do[ If[ PrimeQ[(44*10^n - 17)/9], 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(13) from Kamada data by Robert Price, Dec 13 2010
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STATUS
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approved
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