A268570 Number of immersions of oriented circle into unoriented sphere with n double points and no simple loop.

0, 0, 1, 1, 2, 5, 18, 70, 313, 1440

Offset

1,5

Links

Table of n, a(n) for n=1..10.

Robert Coquereaux and Jean-Bernard Zuber, Maps, immersions and permutations, Journal of Knot Theory and Its Ramifications, Vol. 25, No. 8 (2016), 1650047; arXiv preprint, arXiv:1507.03163 [math.CO], 2015-2016. See Table 6.

Crossrefs

Cf. A008988, A007756, A268568, A268569, A268571, A268572.

Sequence in context: A014271 A073157 A365120 * A141494 A189843 A045612

Adjacent sequences: A268567 A268568 A268569 * A268571 A268572 A268573

Keyword

nonn,more

Author

N. J. A. Sloane, Mar 03 2016

Extensions

Name clarified by Andrey Zabolotskiy, Jun 09 2024

Status

approved