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A108332
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Integers k such that 10^k - 89 is prime.
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2
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OFFSET
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1,1
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COMMENTS
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637 corresponds to a certified prime (Primo 2.2.0 beta). - Ryan Propper, Nov 06 2005
No additional terms < 40000.
See Kamada link - primecount.txt for terms, primesize.txt for discovery details including probable or proved primes - search on "9w11".
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LINKS
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Table of n, a(n) for n=1..5.
Makoto Kamada, List of near-repdigit-related prime numbers.
Index entries for primes involving repunits.
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EXAMPLE
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k = 3 is a term because 10^3 - 89 = 1000 - 89 = 911, which is prime.
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MATHEMATICA
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Do[If[PrimeQ[10^n - 89], Print[n]], {n, 2, 10^4}] (* Ryan Propper *)
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CROSSREFS
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Cf. A089675, A095714, A092767.
Sequence in context: A264577 A165770 A226148 * A256115 A066685 A076155
Adjacent sequences: A108329 A108330 A108331 * A108333 A108334 A108335
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KEYWORD
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nonn,more,changed
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AUTHOR
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Julien Peter Benney (jpbenney(AT)ftml.net), Jun 30 2005
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EXTENSIONS
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a(5) from Robert Price, Dec 15 2010
Edited by Ray Chandler, Dec 23 2010
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STATUS
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approved
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