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A141254
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Number of permutations that lie in the cyclic closure of Av(123) - i.e. at least one cyclic rotation of the permutation avoids the pattern 123.
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1
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1, 2, 6, 24, 110, 510, 2268, 9632, 39492, 158190, 624745, 2447808, 9552244, 37214086, 144932760, 564676096, 2201735552, 8592780798, 33568042425, 131261440720, 513747571680, 2012524130518, 7890178181831, 30957296889264
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OFFSET
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1,2
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REFERENCES
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M. D. Atkinson, M. H. Albert, R. E. L. Aldred, H.P. van Ditmarsch, C.C. Handley, D.A. Holton, D. J. McCaughan, C. Monteith, Cyclically closed pattern classes of permutations, Australasian J. Combinatorics 38 (2007), 87-100.
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LINKS
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Table of n, a(n) for n=1..24.
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FORMULA
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a(n) = n * (C(n) - 2^n + binomial(n,2) + 2) for n >= 4
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EXAMPLE
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a(5)=110 because 110 permutations of length 5 have at least one cyclic rotation which avoids 123.
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CROSSREFS
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Cf. A141253.
Sequence in context: A189255 A177519 A214762 * A216879 A138020 A046646
Adjacent sequences: A141251 A141252 A141253 * A141255 A141256 A141257
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KEYWORD
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nonn
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AUTHOR
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Vincent Vatter, Jun 17 2008
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STATUS
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approved
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