%I #12 Jun 30 2023 12:18:23
%S 1,6,20,101,327,1560,5333,24727,88422,403552
%N Number of continuations with reflective symmetry arising in matrix method for enumerating Hamiltonian cycles on 2n X 2n grid.
%H Ed Wynn, <a href="http://arxiv.org/abs/1402.0545">Enumeration of nonisomorphic Hamiltonian cycles on square grid graphs</a>, arXiv preprint arXiv:1402.0545 [math.CO], 2014.
%Y Cf. A003763, A143246, A209077, A222065, A238115, A238116, A238117.
%K nonn,hard,more
%O 1,2
%A _N. J. A. Sloane_, Mar 05 2014