A268558 Arises in counting maps on a surface: see Coquereaux-Zuber (2015) for precise definition.

2, 8, 34, 182, 1300, 12634, 153598, 2231004, 37250236, 699699968, 14574247086, 333121322514, 8286605836248, 222824153996898, 6439779836400464, 199051769194393718, 6552226226766384216, 228826838199807593530

Offset

1,1

Links

Table of n, a(n) for n=1..18.

R. de Mello Koch, S. Ramgoolam, Strings from Feynman graph counting: Without large N, Phys. Rev. D 85 (2012) 026007. Different from a(7) onwards.

R. Coquereaux, J.-B. Zuber, Maps, immersions and permutations, arXiv preprint arXiv:1507.03163, 2015. Also J. Knot Theory Ramifications 25, 1650047 (2016),

Crossrefs

Euler transform of A170946.

Sequence in context: A121894 A061370 A126328 * A191569 A229812 A346413

Adjacent sequences: A268555 A268556 A268557 * A268559 A268560 A268561

Keyword

nonn

Author

N. J. A. Sloane, Mar 02 2016

Extensions

a(11) and beyond from Euler transform of A170946 - R. J. Mathar, Apr 07 2022

Status

approved