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A008980
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Number of immersions of the oriented circle into the oriented plane with n double points.
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6
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2, 3, 10, 39, 204, 1262, 8984, 67959, 544504, 4535030, 39004772
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,1
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REFERENCES
| V. I. Arnold, Topological Invariants of Plane Curves..., American Math. Soc., 1994, p. 16.
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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.
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CROSSREFS
| Cf. A008981, A008982, A008983, A008984, A008985, A054993.
Sequence in context: A144720 A164933 A003048 * A064183 A050381 A129716
Adjacent sequences: A008977 A008978 A008979 * A008981 A008982 A008983
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KEYWORD
| nonn,nice
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
| Additional comments from Sergei V. Duzhin (duzhin(AT)botik.ru), Nov 11, 2000.
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