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A187804
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Number of circular permutations of length n whose n flattenings are all not derangements
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0
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OFFSET
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3,3
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COMMENTS
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Circular permutations are permutations whose indices are from the ring of integers modulo n. For a circular permutation pi, a flattening at position k<n gives a straight permutation which preserves the relative order of pi. For example, the circular permutation (0,2,1) has the flattenings 021, 210, and 102. Note these three flattenings are all not derangements, so a(3) counts (0,2,1).
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LINKS
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EXAMPLE
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For n=5 the a(5)=3 solutions are (0,3,1,4,2), (0,4,3,2,1), and (0,2,4,1,3).
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CROSSREFS
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KEYWORD
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nonn,more
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AUTHOR
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STATUS
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approved
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