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Search: id:A163800
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| A163800 |
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a(n) is the n-th J_20-prime (Josephus_20 prime) Place the numbers 1..N (N>=2) on a circle and cyclicly mark the 20th unmarked number until all N numbers are marked. The order in which the N numbers are marked defines a permutation; N is a J_20-prime if this permutation consists of a single cycle of length N. |
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19
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| 2, 5, 30, 54, 81, 109, 149, 186, 513, 1089, 8158, 8533, 17178, 34478, 913274, 976402
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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There are 16 J_20-primes in the interval 2..1000000 only. No formula is known; the J_20-primes were found by exhaustive search.
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REFERENCES
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R. L. Graham, D.E. Knuth & O. Patashnik, Concrete Mathematics (1989), Addison-Wesley, Reading, MA. Sections 1.3 & 3.3.
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LINKS
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P. R. J. Asveld, Permuting Operations on Strings - Their Permutations and Their Primes (2009), TR-CTIT-09-26, Dept. of CS, Twente University of Technology, Enschede, The Netherlands.
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EXAMPLE
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2 is a J_20-prime (trivial).
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CROSSREFS
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See A163782 through A163799 for J_2- through J_19-primes.
Sequence in context: A158866 A101078 A109739 this_sequence A019027 A019031 A140786
Adjacent sequences: A163797 A163798 A163799 this_sequence A163801 A163802 A163803
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KEYWORD
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nonn
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AUTHOR
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P. R. J. Asveld (infprja(AT)cs.utwente.nl), Aug 04 2009, Aug 12 2009
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