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URL: https://oeis.org/A008980

⇱ A008980 - OEIS

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A008980
Number of immersions of the oriented circle into the oriented plane with n double points.
6
2, 3, 10, 39, 204, 1262, 8984, 67959, 544504, 4535030, 39004772, 344217402, 3103896536
OFFSET
0,1
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.
PROG
(Pascal) Cf. link.
CROSSREFS
KEYWORD
nonn,nice,more
EXTENSIONS
Additional comments from Sergei Duzhin, Nov 11 2000
a(11)-a(12) from Sean A. Irvine, Apr 19 2018
STATUS
approved