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A103077
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Numbers n such that 8*10^n + 2*R_n + 7 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, 5, 8, 14, 55, 103, 331, 1067, 13711, 24397
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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 (74*10^n+61)/9 is prime.
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LINKS
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Table of n, a(n) for n=1..11.
Makoto Kamada, Factorizations of 822...229.
Index entries for primes involving repunits.
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MATHEMATICA
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Do[ If[ PrimeQ[(74*10^n + 61)/9], Print[n]], {n, 0, 10000}]
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CROSSREFS
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Sequence in context: A023674 A139218 A017988 * A090980 A183409 A024808
Adjacent sequences: A103074 A103075 A103076 * A103078 A103079 A103080
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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)-a(11) from Kamada data by Robert Price, Dec 14 2010
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STATUS
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approved
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