A268571 Arises in counting maps on a surface: see Coquereaux-Zuber (2015) for precise definition.

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

Offset

1,5

Links

Table of n, a(n) for n=1..10.

R. Coquereaux, J.-B. Zuber, Maps, immersions and permutations, arXiv preprint arXiv:1507.03163, 2015. Also J. Knot Theory Ramifications 25, 1650047 (2016), DOI: http://dx.doi.org/10.1142/S0218216516500474

Guy Valette, A Classification of Spherical Curves Based on Gauss Diagrams, Arnold Math. J. (2016) 2:383-405, DOI 10.1007/s40598-016-0049-3. See Table 7 (although it is not certain that this is the same sequence - N. J. A. Sloane, Jul 17 2017).

Crossrefs

Cf. A008989.

Sequence in context: A148393 A148394 A291685 * A001428 A055726 A101500

Adjacent sequences: A268568 A268569 A268570 * A268572 A268573 A268574

Keyword

nonn,more

Author

N. J. A. Sloane, Mar 03 2016

Status

approved