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 A141253 Number of permutations that lie in the cyclic closure of Av(132) - i.e. at least one cyclic rotation of the permutation avoids the pattern 132. 1
 1, 2, 6, 24, 100, 408, 1631, 6440, 25263, 98790, 385803, 1506156, 5881057, 22974406, 89804910, 351279584, 1375035208, 5386203792, 21113167346, 82816267480, 325055630634, 1276635121388, 5016837177052, 19725798613152, 77601159558800 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 REFERENCES 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. R. Brignall, S. Huczynska, V. Vatter, Simple permutations and algebraic generating functions, J. Combinatorial Theory, Series A 115 (2008), 423-441. LINKS FORMULA g.f. = (1-4x+4x^2-4x^3-(1-2x)sqrt(1-4x)) / (2x(1-x)^2sqrt(1-4x)). a(n) = n(C(n) - C(n-1) - ... - C(1)), where C(n) denotes the n-th Catalan number. EXAMPLE a(5)=100 because 100 permutations of length 5 have at least one cyclic rotation which avoids 132. CROSSREFS Cf. A141254. Sequence in context: A060725 A150299 A094012 * A078486 A129817 A128652 Adjacent sequences:  A141250 A141251 A141252 * A141254 A141255 A141256 KEYWORD nonn AUTHOR Vincent Vatter, Jun 17 2008 STATUS approved

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Last modified May 22 05:06 EDT 2013. Contains 225511 sequences.