|
|
A008986
|
|
Number of immersions of oriented circle into oriented sphere with n double points.
|
|
15
|
|
|
1, 1, 3, 9, 37, 182, 1143, 7553, 54559, 412306, 3251240, 26478264, 221714164, 1900103364, 16613990484, 147816411921, 1335367515821
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,3
|
|
COMMENTS
|
a(10) = 3251240 by sampling method (to be confirmed, cf. ref. arXiv:1507.03163). - Robert Coquereaux, Nov 23 2015
|
|
REFERENCES
|
V. I. Arnold, Topological Invariants of Plane Curves and Caustics, American Math. Soc., 1994, p. 18.
|
|
LINKS
|
R. Coquereaux and J.-B. Zuber, Maps, immersions and permutations, arXiv preprint arXiv:1507.03163 [math.CO], 2015-2016. Also J. Knot Theory Ramifications 25, 1650047 (2016), DOI: http://dx.doi.org/10.1142/S0218216516500474
|
|
PROG
|
(Magma) /* For Magma program see A260285. */
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,more
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|