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Search: id:A095714
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| A095714 |
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Numbers n such that 90*R_n + 1 is prime, where R_n = 11...1 is the repunit (A002275) of length n. |
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+0
12
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| 3, 5, 7, 33, 45, 105, 197, 199, 281, 301, 317, 1107, 1657, 3395, 35925, 37597
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Also numbers n such that 10^n - 9 is a prime.
No more terms below 4300. Robert G. Wilson v Oct 15 2004.
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LINKS
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Index entries for primes involving repunits
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EXAMPLE
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a(2) = 5, since 10^5 - 9 = 99991, which is prime
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MATHEMATICA
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Do[ If[ PrimeQ[10^n - 9], Print[n]], {n, 0, 7000}]
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CROSSREFS
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Cf. A088275.
Adjacent sequences: A095711 A095712 A095713 this_sequence A095715 A095716 A095717
Sequence in context: A006378 A002396 A029508 this_sequence A137864 A069969 A067232
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KEYWORD
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nonn
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AUTHOR
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Alonso Delarte (alonso.delarte(AT)gmail.com), Jul 07 2004
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EXTENSIONS
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More terms from Robert G. Wilson v (rgwv(AT)rgwv.com), Oct 15 2004
2 more terms from Jason Earls (jcearls(AT)cableone.net), Jan 07 2008
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