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A008980 Number of immersions of the oriented circle into the oriented plane with n double points. 6

%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

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