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%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
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