A289678 Number of hypermaps which are self-equivalent with respect to reversing the colors of the nodes and which have n edges.

1, 1, 3, 6, 15, 42, 131, 442, 1551, 5723, 22171, 89156, 370199, 1589240, 7020127, 31906974

Offset: 1

Author

N. J. A. Sloane, Aug 03 2017

Keywords

• nonn
• more

Links

• M. Deryagina, On the enumeration of hypermaps which are self-equivalent with respect to reversing the colors of vertices, Preprint 2016.

Crossrefs

Cf. A057005, A234278.

Formula

a(n) = 2*A234278(n) - 2*A057005(n).