A268572 - OEIS

A268572

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

0, 0, 2, 1, 4, 9, 38, 133, 640, 2864

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,3

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 6.

FORMULA

a(2*n) = A268568(2*n), a(2*n+1) = 2 * A268569(2*n+1). - Andrey Zabolotskiy, Jun 05 2024

CROSSREFS

Cf. A268561, A268568, A268569, A268573.

Sequence in context: A254199 A343398 A097949 * A343909 A117338 A279927

Adjacent sequences: A268569 A268570 A268571 * A268573 A268574 A268575

KEYWORD

nonn,more

AUTHOR

N. J. A. Sloane, Mar 03 2016

EXTENSIONS

Name clarified by Andrey Zabolotskiy, Jun 08 2024

STATUS

approved