A268561 Number of bicolored immersions of unoriented circle into oriented sphere with n double points.

1, 2, 3, 12, 37, 198, 1143, 7658, 54559, 413086, 3251240, 26484550, 221714164, 1900156948, 16613990484, 147816887598, 1335367515821

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 Table 2, Table 5, and Table 9, line UOc.

Crossrefs

Cf. A008986, A008987.

Formula

a(2*n) = A008986(2*n), a(2*n+1) = 2 * A008987(2*n+1). - Andrey Zabolotskiy, Jun 05 2024

Extensions

Name clarified and a(0), a(11)-a(16) added using formula by Andrey Zabolotskiy, Jun 08 2024