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A103027
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Numbers n such that 6*10^n + R_n + 2 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
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1
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2, 3, 5, 11, 12, 23, 75, 101, 122, 173, 647, 2015, 2684, 11700, 19625
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OFFSET
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1,1
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COMMENTS
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Also numbers n such that (55*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[(55*10^n + 17)/9], Print[n]], {n, 0, 10000}]
Select[Range[0, 10000], PrimeQ[(55 10^# + 17)/9] &] (* Vincenzo Librandi, Sep 10 2015 *)
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PROG
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(Magma) [n: n in [0..500]| IsPrime((55*10^n + 17) div 9)]; // Vincenzo Librandi, Sep 10 2015
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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(14)-a(15) from Kamada data by Robert Price, Dec 12 2010
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STATUS
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approved
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