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

2, 3, 10, 39, 204, 1262, 8984, 67959, 544504, 4535030, 39004772, 344217402, 3103896536

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn
• nice
• more

References

• V. I. Arnold, Topological Invariants of Plane Curves and Caustics, American Math. Soc., 1994, p. 16.

Links

• S. M. Gusein-Zade and F. S. Duzhin, On the number of topological types of plane curves; (Russian) Uspekhi Mat. Nauk 53 (1998), no. 3(321), 197-198. English translation: Russian Mathematical Surveys 53 (1998) 626-627.
• S. M. Gusein-Zade and F. S. Duzhin, Enumeration of plane curves with up to 10 selfintersections, Pascal program and result table, 05 Apr 1998.

Crossrefs

Cf. A008981, A008982, A008983, A008984, A008985, A054993.

Programs

Pascal

Cf. link.

Extensions

Additional comments from Sergei Duzhin, Nov 11 2000

a(11)-a(12) from Sean A. Irvine, Apr 19 2018