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 A173469 Number of permutations of length n that can be sorted in 2^(n-1)-1 steps of Elizalde and Winkler's homing algorithm 0
 1, 2, 5, 16, 62, 280, 1440, 8296, 52864, 368848, 2794864, 22842048, 200201408, 1872466944, 18608903968, 195778297664, 2173272774016, 25380361760000, 311011886153856, 3989579297299712, 53458990592638976, 746817531317769728 (list; graph; refs; listen; history; text; internal format)
 OFFSET 2,2 COMMENTS The maximum number of steps that the homing algorithm can take to sort a permutation of length n is 2^(n-1)-1. This sequence counts permutations for which it is possible to use these many steps. REFERENCES S. Elizalde and P. Winkler, Sorting by Placement and Shift, Proceedings of the Twentieth Annual ACM-SIAM Symposium on Discrete Algorithms, SODA 2009. LINKS S. Elizalde and P. Winkler, Sorting by placement and shift FORMULA a(n) is the coefficient of t^n in the generating function F(t,t), where F(u,v) satisfies the partial differential equation F(u,v)=u*v+u*v*D_u(f)+u*v*D_v(f)-u^2*v^2*D_u(D_v(f)). CROSSREFS Sequence in context: A124531 A129578 A005387 * A138549 A210667 A144188 Adjacent sequences:  A173466 A173467 A173468 * A173470 A173471 A173472 KEYWORD nonn AUTHOR Sergi Elizalde, Feb 18 2010 STATUS approved

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Last modified May 15 04:03 EDT 2021. Contains 343909 sequences. (Running on oeis4.)