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A102973
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Numbers n such that 3*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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0, 2, 3, 5, 8, 14, 77, 195, 218, 957, 1052, 1163, 1485, 1731, 1970, 3237, 17354
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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 (32*10^n+31)/9 is prime.
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LINKS
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Table of n, a(n) for n=1..17.
Makoto Kamada, Factorizations of 355...559.
Index entries for primes involving repunits.
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MATHEMATICA
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Do[ If[ PrimeQ[(32*10^n+31)/9], Print[n]], {n, 0, 10000}]
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CROSSREFS
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Sequence in context: A196118 A104880 A152478 * A066372 A058519 A181065
Adjacent sequences: A102970 A102971 A102972 * A102974 A102975 A102976
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KEYWORD
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more,nonn
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AUTHOR
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Robert G. Wilson v, Dec 17 2004
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EXTENSIONS
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Addition of a(17) from Kamada data by Robert Price, Dec 12 2010
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STATUS
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approved
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