A006425 Number of rooted toroidal maps with 2 vertices and n faces and no isthmuses. (Formerly M3700)

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

Offset

1,1

References

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

Links

Table of n, a(n) for n=1..22.

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.

Sequence in context: A054951 A215843 A048957 * A065930 A018807 A216410

Adjacent sequences: A006422 A006423 A006424 * A006426 A006427 A006428

Keyword

nonn

Author

N. J. A. Sloane

Extensions

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

Status

approved