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A103023
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Numbers n such that 5*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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OFFSET
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1,1
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COMMENTS
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Also numbers n such that (53*10^n-17)/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 588...887.
Index entries for primes involving repunits.
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MATHEMATICA
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Do[ If[ PrimeQ[(53*10^n - 17)/9], Print[n]], {n, 0, 10000}]
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CROSSREFS
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Sequence in context: A134136 A185165 A058775 * A111247 A045656 A129342
Adjacent sequences: A103020 A103021 A103022 * A103024 A103025 A103026
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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(9) from Kamada data by Robert Price, Dec 13 2010
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STATUS
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approved
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