cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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

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%I A268561 #11 Jun 09 2024 09:03:58
%S A268561 1,2,3,12,37,198,1143,7658,54559,413086,3251240,26484550,221714164,
%T A268561 1900156948,16613990484,147816887598,1335367515821
%N A268561 Number of bicolored immersions of unoriented circle into oriented sphere with n double points.
%H A268561 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 2, Table 5, and Table 9, line UOc.
%F A268561 a(2*n) = A008986(2*n), a(2*n+1) = 2 * A008987(2*n+1). - _Andrey Zabolotskiy_, Jun 05 2024
%Y A268561 Cf. A008986, A008987.
%K A268561 nonn,more
%O A268561 0,2
%A A268561 _N. J. A. Sloane_, Mar 02 2016
%E A268561 Name clarified and a(0), a(11)-a(16) added using formula by _Andrey Zabolotskiy_, Jun 08 2024