A268564 Number of immersions of unoriented circle into oriented sphere with 2n double points such that two different choices of orientation of the circle are not related by geotopy.

0, 1, 16, 555, 27155, 1624602, 110848296, 8306916404, 667683029392

Offset: 0

Author

N. J. A. Sloane, Mar 02 2016

Keywords

• nonn
• more

Links

• 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 Eq. (16), s_s.

Crossrefs

Cf. A008986, A008987, A268563.

Formula

a(n) = A008986(2*n) - A008987(2*n). - Andrey Zabolotskiy, Jun 05 2024

Extensions

Name clarified and a(0), a(6)-a(8) added using formula by Andrey Zabolotskiy, Jun 08 2024