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A103100
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Numbers n such that 9*10^n + 5*R_n - 4 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
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1
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3, 6, 18, 30, 88, 93, 154, 177, 228, 573, 897, 981, 1416, 1450, 3366, 4932, 5194, 13479, 18609, 23346
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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 (86*10^n-41)/9 is prime.
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LINKS
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Table of n, a(n) for n=1..20.
Makoto Kamada, Factorizations of 955...551.
Index entries for primes involving repunits.
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MATHEMATICA
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Do[ If[ PrimeQ[(86*10^n - 41)/9], Print[n]], {n, 0, 10000}]
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CROSSREFS
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Sequence in context: A088339 A064400 A117863 * A101726 A034457 A026532
Adjacent sequences: A103097 A103098 A103099 * A103101 A103102 A103103
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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(18)-a(20) from Kamada data by Robert Price, Dec 14 2010
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STATUS
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approved
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