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%I #30 May 21 2019 18:56:21
%S 1,1,4,13,72,390,2880,21672,201600,1935360,21772800,253756800,
%T 3353011200,45924278400
%N Number of cds-sortable permutations in S_n. That is, number of permutations for which application of some sequence of context directed swaps ("cds" operations) terminates in the identity.
%H K. L. M. Adamyk, E. Holmes, G. R. Mayfield, D. J. Moritz, M. Scheepers, B. E. Tenner, and H. C. Wauck, <a href="http://arxiv.org/abs/1410.2353">Sorting permutations: games, genomes, and cycles</a>, arXiv:1410.2353 [math.CO], 2014.
%H C. A. Brown, C. S. Carrillo Vazquez, R. Goswami, S. Heil, M. Scheepers, <a href="https://arxiv.org/abs/1903.xxxxx">The Sortability of Graphs and Matrices under Context Directed Swaps</a>, arXiv:1904.03287 [math.CO], 2019.
%e a(3) = 4 because there are 4 cds-sortable permutations of {1,2,3}. These are, in one-line notation, 123, 132, 213, and 321.
%K nonn,more
%O 1,3
%A _Bridget Tenner_, Dec 15 2014
%E a(11)-a(14) from _Paul Plummer_, Jan 18 2015