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Number of immersions of unoriented circle into unoriented sphere with n double points and no simple loop.
4

%I #18 Jun 10 2024 15:00:41

%S 0,0,1,1,2,5,16,52,205,863

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

%H Robert Coquereaux and Jean-Bernard Zuber, <a href="https://doi.org/10.1142/S0218216516500474">Maps, immersions and permutations</a>, Journal of Knot Theory and Its Ramifications, Vol. 25, No. 8 (2016), 1650047; <a href="https://arxiv.org/abs/1507.03163">arXiv preprint</a>, arXiv:1507.03163 [math.CO], 2015-2016. See Table 6.

%H Guy Valette, <a href="https://doi.org/10.1007/s40598-016-0049-3">A Classification of Spherical Curves Based on Gauss Diagrams</a>, Arnold Math. J. (2016) 2:383-405. See Table 7.

%Y Cf. A008989, A264759, A268568, A268569, A268570, A268572.

%K nonn,more

%O 1,5

%A _N. J. A. Sloane_, Mar 03 2016

%E Name clarified by _Andrey Zabolotskiy_, Jun 09 2024