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A008982
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Number of immersions of the oriented circle into the unoriented plane with n double points.
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6
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1, 2, 5, 21, 102, 640, 4492, 34047, 272252, 2268085, 19502386
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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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), number 3(321), 197-198. English translation: Russian Mathematical Surveys 53 (1998) 626-627.
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CROSSREFS
| Cf. A008980, A008981, A008983, A008984, A008985, A054993.
Sequence in context: A047104 A115087 A008981 * A130471 A002628 A020129
Adjacent sequences: A008979 A008980 A008981 * A008983 A008984 A008985
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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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