%I #7 May 18 2020 14:59:21
%S 0,0,0,0,0,0,22,51,146
%N Number of minimal non-2-stack-sortable permutations of length n.
%D V. Vatter, The Enumeration and Structure of Permutation Classes, Ph. D. Dissertation, Rutgers Univ., Math. Dept., 2006.
%H M. D. Atkinson, M. M. Murphy and N. Ruskuc, <a href="https://doi.org/10.1016/S0304-3975(01)00270-5">Sorting with two ordered stacks in series</a>, Theoret. Comput. Sci. 289 (2002), 205-223.
%H R. E. Tarjan, <a href="https://doi.org/10.1145/321694.321704">Sorting using networks of queues and stacks</a>, JACM, 19 (1972), 341-346.
%K nonn,more
%O 1,7
%A _N. J. A. Sloane_, Nov 17 2005