%I
%S 1,2,28,1504,520176,696179102,5373177281748,166903679914150336,
%T 28636599794306124116062,20262965974179958448766775754
%N Number of Hamiltonian cycles on 2n X 2n grid with at least 180 degree rotational symmetry.
%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, 2014
%Y Cf. A003763.
%K nonn
%O 1,2
%A _N. J. A. Sloane_, Mar 05 2014
