This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A003305 M1860 #21 Oct 22 2023 00:14:45 %S A003305 2,8,40,208,1120,6200,35236,204664,1210392,7266824,44184288 %N A003305 Figure 8's with 2n edges on the square lattice. %C A003305 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 A003305 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). %H A003305 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 A003305 Cf. A002931, A003304. %K A003305 nonn,more %O A003305 4,1 %A A003305 _N. J. A. Sloane_ %E A003305 a(11)-a(14) from _Sean A. Irvine_, Mar 21 2017