A268569 Number of immersions of unoriented circle into oriented sphere with n double points and no simple loop.

0, 0, 1, 1, 2, 6, 19, 74, 320, 1469

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. A008987, A264760, A268568, A268570, A268571, A268572.

Sequence in context: A343417 A150119 A361489 * A181770 A138800 A008989

Adjacent sequences: A268566 A268567 A268568 * A268570 A268571 A268572

Keyword

nonn,more

Author

N. J. A. Sloane, Mar 03 2016

Extensions

Name clarified by Andrey Zabolotskiy, Jun 09 2024

Status

approved