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A103094
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Numbers n such that 9*10^n + 2*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 (83*10^n+7)/9 is prime.
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LINKS
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Table of n, a(n) for n=1..10.
Makoto Kamada, Factorizations of 922...223.
Index entries for primes involving repunits.
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MATHEMATICA
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Do[ If[ PrimeQ[(83*10^n + 7)/9], Print[n]], {n, 0, 10000}]
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CROSSREFS
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Sequence in context: A177831 A115706 A031394 * A108928 A097812 A176333
Adjacent sequences: A103091 A103092 A103093 * A103095 A103096 A103097
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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(10) from Kamada data by Robert Price, Dec 14 2010
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STATUS
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approved
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