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A103104
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Numbers n such that 9*10^n + 6*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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1, 2, 4, 7, 13, 28, 58, 86, 92, 108, 1408, 1486, 1712, 2674, 3880, 5536, 7588, 7650, 10558, 15532, 17959
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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 (29*10^n+1)/3 is prime.
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LINKS
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Table of n, a(n) for n=1..21.
Makoto Kamada, Factorizations of 966...667.
Index entries for primes involving repunits.
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MATHEMATICA
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Do[ If[ PrimeQ[(29*10^n + 1)/3], Print[n]], {n, 0, 10000}]
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CROSSREFS
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Sequence in context: A025246 A112740 A136408 * A103480 A024826 A102114
Adjacent sequences: A103101 A103102 A103103 * A103105 A103106 A103107
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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(19)-a(21) from Kamada data by Robert Price, Dec 14 2010
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STATUS
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approved
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