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A102939
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Numbers n such that 10^n + 6*R_n - 3 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
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1
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1, 2, 3, 18, 177, 324, 388, 392, 404, 531, 1083, 12546, 22443
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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 (5*10^n-11)/3 is prime.
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LINKS
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Table of n, a(n) for n=1..13.
Makoto Kamada, Factorizations of 166...663.
Index entries for primes involving repunits.
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MATHEMATICA
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Do[ If[ PrimeQ[(5*10^n - 11)/3], Print[n]], {n, 0, 10000}]
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CROSSREFS
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Sequence in context: A184719 A076016 A107095 * A073983 A139319 A092925
Adjacent sequences: A102936 A102937 A102938 * A102940 A102941 A102942
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KEYWORD
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more,nonn
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AUTHOR
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Robert G. Wilson v, Dec 16 2004
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EXTENSIONS
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Addition of a(12)-a(13) from Kamada data by Robert Price, Dec 12 2010
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STATUS
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approved
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