A003305 Figure 8's with 2n edges on the square lattice.

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

Offset: 4

Author

N. J. A. Sloane

Keywords

• nonn
• more

Comments

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

References

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

Links

• S. G. Whittington and J. P. Valleau, Figure eights on the square lattice: enumeration and Monte Carlo estimation, J. Phys. A 3 (1970), 21-27.

Crossrefs

Cf. A002931, A003304.

Extensions

a(11)-a(14) from Sean A. Irvine, Mar 21 2017