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A102947
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Numbers n such that 2*10^n-3 is prime.
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2
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1, 2, 3, 4, 13, 14, 76, 237, 872, 988, 1280, 1370, 2686, 3612, 4051, 4645, 9162, 10856, 25959, 64882
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| Numbers n such that 10^n + 8*R_n - 2 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
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LINKS
| Makoto Kamada, Factorizations of 199...997.
Index entries for primes involving repunits.
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MATHEMATICA
| Do[ If[ PrimeQ[2*10^n - 3], Print[n]], {n, 0, 10000}]
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CROSSREFS
| Sequence in context: A165302 A117342 A126129 * A162222 A010346 A089142
Adjacent sequences: A102944 A102945 A102946 * A102948 A102949 A102950
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KEYWORD
| more,nonn
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AUTHOR
| Robert G. Wilson v (rgwv(AT)rgwv.com), Dec 16 2004
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EXTENSIONS
| Addition of a(18)-a(20) from Kamada data by Robert Price (pamandbobprice(AT)yahoo.com), Dec 09 2010
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