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A103019
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Numbers n such that 5*10^n + 7*R_n - 6 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
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1
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2, 6, 9, 27, 30, 48, 141, 150, 372, 422, 1097, 3570, 4607, 5289, 10734, 11550
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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 (52*10^n-61)/9 is prime.
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LINKS
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Table of n, a(n) for n=1..16.
Makoto Kamada, Factorizations of 577...771.
Index entries for primes involving repunits.
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MATHEMATICA
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Do[ If[ PrimeQ[(52*10^n - 61)/9], Print[n]], {n, 0, 10000}]
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CROSSREFS
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Sequence in context: A006746 A205875 A121624 * A101823 A093397 A082459
Adjacent sequences: A103016 A103017 A103018 * A103020 A103021 A103022
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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 18 2005
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EXTENSIONS
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Addition of a(15)-a(16) from Kamada data by Robert Price, Dec 12 2010
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STATUS
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approved
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