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A103092
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Numbers n such that 9*10^n-7 is prime.
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1
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1, 6, 9, 10, 12, 13, 23, 61, 194, 233, 549, 765, 973, 1061, 1186, 1853, 3713, 6789, 7254, 7765, 9025, 10855, 23640, 31440, 31839, 32287
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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 8*10^n + 9*R_n - 6 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
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LINKS
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Table of n, a(n) for n=1..26.
Makoto Kamada, Factorizations of 899...993.
Index entries for primes involving repunits.
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MATHEMATICA
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Do[ If[ PrimeQ[9*10^n - 7], Print[n]], {n, 0, 10000}]
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CROSSREFS
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Sequence in context: A070598 A124257 A066385 * A104523 A091886 A111774
Adjacent sequences: A103089 A103090 A103091 * A103093 A103094 A103095
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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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One more term from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 01 2008
a(23)-a(26) from Kamada data by Robert Price, Dec 14 2010
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STATUS
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approved
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