A006425 Number of rooted toroidal maps with 2 vertices and n faces and no isthmuses.

4, 79, 900, 7885, 59080, 398846, 2499096, 14805705, 83969600, 459868530, 2447439384, 12718070274, 64766697520, 324156347260, 1598200903280, 7776728909121, 37404399901296, 178060831286890, 839857764202520, 3928581810398630, 18239060530882224, 84101317494787684

Offset: 1

Author

N. J. A. Sloane

Keywords

• nonn

References

• N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

• T. R. S. Walsh and A. B. Lehman, Counting rooted maps by genus. III: Nonseparable maps, J. Combinatorial Theory Ser. B 18 (1975), 222-259.

Crossrefs

A diagonal of A343092.

Extensions

Name clarified and terms a(11) and beyond from Andrew Howroyd, Apr 05 2021