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A309508
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Number of cyclic permutations of length n avoiding the pattern 321.
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3
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1, 1, 2, 4, 10, 24, 66, 178, 512, 1486, 4446, 13468
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OFFSET
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1,3
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COMMENTS
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The maps sending a permutation to its inverse or to its reverse-complement define two commuting involutions on these sets of permutations.
The next terms in the sequence could be 41648, 130178, though these are counting Dyck words such that an associated permutation is cyclic, related but not obviously equivalent combinatorial objects. (End)
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LINKS
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EXAMPLE
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For n=3, there are two such permutations, 231 and 312.
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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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