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A103091
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Numbers n such that 8*10^n + 7*R_n + 2 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
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2
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1, 3, 6, 31, 36, 61, 117, 229, 339, 3165, 3958, 5277, 5343, 6079, 6535, 8485, 15084, 34537
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history;
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internal format)
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OFFSET
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1,2
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COMMENTS
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Also numbers n such that (79*10^n+11)/9 is prime.
a(19) > 10^5. - Robert Price, Oct 27 2015
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LINKS
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Table of n, a(n) for n=1..18.
Makoto Kamada, Prime numbers of the form 877...779.
Index entries for primes involving repunits.
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FORMULA
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a(n) = A101078(n) + 1.
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MATHEMATICA
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Do[ If[ PrimeQ[(79*10^n + 11)/9], Print[n]], {n, 0, 10000}]
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CROSSREFS
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Cf. A002275, A101078.
Sequence in context: A117805 A154135 A182274 * A186940 A101751 A274999
Adjacent sequences: A103088 A103089 A103090 * A103092 A103093 A103094
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KEYWORD
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more,nonn
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AUTHOR
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Robert G. Wilson v, Jan 19 2005
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EXTENSIONS
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a(17) from Kamada data by Robert Price, Dec 14 2010
a(18) from Erik Branger May 01 2013 by Ray Chandler, Aug 16 2013
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STATUS
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approved
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