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A103089
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Numbers n such that 8*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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OFFSET
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1,1
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COMMENTS
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Also numbers n such that (79*10^n-61)/9 is prime.
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LINKS
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Table of n, a(n) for n=1..9.
Makoto Kamada, Factorizations of 877...771.
Index entries for primes involving repunits.
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MATHEMATICA
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Do[ If[ PrimeQ[(79*10^n - 61)/9], Print[n]], {n, 0, 10000}]
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CROSSREFS
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Sequence in context: A078984 A041257 A041411 * A041601 A041827 A042089
Adjacent sequences: A103086 A103087 A103088 * A103090 A103091 A103092
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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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1 more term. Next term exceeds 50000. Sean A. Irvine, Sep 10 2009
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STATUS
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approved
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