Needs more terms and a b-file (note that one of the links gives the first 201 terms).
Table of n, a(n) for n=2..24.
Marston Conder, Home Page (Contains tables of regular maps, hypermaps and polytopes, trivalent symmetric graphs, and surface actions)
Marston Conder, Non-orientable proper regular hypermaps of genus 2 to 202
Sequence in context: A082512 A068385 A318657 * A225749 A227985 A071086
Adjacent sequences: A286274 A286275 A286276 * A286278 A286279 A286280
N. J. A. Sloane, May 08 2017