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%I #18 Feb 26 2020 13:38:13
%S 2,3,10,39,204,1262,8984,67959,544504,4535030,39004772,344217402,
%T 3103896536
%N Number of immersions of the oriented circle into the oriented plane with n double points.
%D V. I. Arnold, Topological Invariants of Plane Curves and Caustics, American Math. Soc., 1994, p. 16.
%H S. M. Gusein-Zade and F. S. Duzhin, <a href="http://www.botik.ru/~duzhin/as/dataprog/">On the number of topological types of plane curves</a>; (Russian) Uspekhi Mat. Nauk 53 (1998), no. 3(321), 197-198. <a href="https://pdfs.semanticscholar.org/8e15/31bc512538a6e0dcd2f22d638d94c5682610.pdf">English translation</a>: Russian Mathematical Surveys 53 (1998) 626-627.
%H S. M. Gusein-Zade and F. S. Duzhin, Enumeration of plane curves with up to 10 selfintersections, <a href="http://www.pdmi.ras.ru/~arnsem/dataprog/">Pascal program and result table</a>, 05 Apr 1998.
%o (Pascal) Cf. link.
%Y Cf. A008981, A008982, A008983, A008984, A008985, A054993.
%K nonn,nice,more
%O 0,1
%A _N. J. A. Sloane_
%E Additional comments from _Sergei Duzhin_, Nov 11 2000
%E a(11)-a(12) from _Sean A. Irvine_, Apr 19 2018