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Search: id:A102946
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| A102946 |
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Numbers n such that 2*10^n-7 is prime. |
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+0
2
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| 1, 2, 3, 4, 6, 16, 21, 28, 48, 82, 122, 130, 282, 304, 4602, 12984, 13614
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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Also numbers n such that 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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Makoto Kamada, Factorizations of 199...993.
Index entries for primes involving repunits.
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MATHEMATICA
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Do[ If[ PrimeQ[2*10^n - 7], Print[n]], {n, 0, 10000}]
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CROSSREFS
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Sequence in context: A056712 A002087 A049288 this_sequence A026094 A069860 A084391
Adjacent sequences: A102943 A102944 A102945 this_sequence A102947 A102948 A102949
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KEYWORD
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more,nonn
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AUTHOR
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Robert G. Wilson v (rgwv(AT)rgwv.com), Dec 16 2004
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EXTENSIONS
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More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008
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