%I M1860 #21 Oct 22 2023 00:14:45

%S 2,8,40,208,1120,6200,35236,204664,1210392,7266824,44184288

%N Figure 8's with 2n edges on the square lattice.

%C Rotations and reflections are distinct. 2n is the total number of edges in the figure. Each "figure 8" is two of the polygons counted by A002931 intersecting at a single point. Like A003304 but now the smaller loop need not be a simple square. - _Sean A. Irvine_, Mar 21 2017

%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

%H S. G. Whittington and J. P. Valleau, <a href="https://doi.org/10.1088/0305-4470/3/1/003">Figure eights on the square lattice: enumeration and Monte Carlo estimation</a>, J. Phys. A 3 (1970), 21-27.

%Y Cf. A002931, A003304.

%K nonn,more

%O 4,1

%A _N. J. A. Sloane_

%E a(11)-a(14) from _Sean A. Irvine_, Mar 21 2017