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A163786
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a(n) is the n-th J_6-prime (Josephus_6 prime).
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2
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2, 13, 17, 18, 34, 49, 93, 97, 106, 225, 401, 745, 2506, 3037, 3370, 4713, 5206, 8585, 13418, 32237, 46321, 75525, 97889, 106193, 238513, 250657, 401902, 490118
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OFFSET
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1,1
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COMMENTS
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Place the numbers 1..N (N>=2) on a circle and cyclicly mark the 6th unmarked number until all N numbers are marked. The order in which the N numbers are marked defines a permutation; N is a J_6-prime if this permutation consists of a single cycle of length N.
There are 28 J_6-primes in the interval 2..1000000 only. No formula is known; the J_6-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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EXAMPLE
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2 is a J_6-prime (trivial).
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CROSSREFS
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KEYWORD
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nonn,more,changed
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AUTHOR
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STATUS
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approved
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