A006426 Number of rooted toroidal maps with 3 vertices and n faces and no isthmuses. (Formerly M4751)

10, 340, 5846, 71372, 706068, 6052840, 46759630, 333746556, 2238411692, 14277544216, 87376309020, 516495616120, 2964332933800, 16586670357200, 90782049175614, 487329793111260, 2571575908919740, 13364166071956280, 68507393061864020, 346874109053120616

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..20.

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: A288684 A046747 A338799 * A029698 A197598 A197982

Adjacent sequences: A006423 A006424 A006425 * A006427 A006428 A006429

Keyword

nonn

Author

N. J. A. Sloane

Extensions

Name clarified and terms a(10) and beyond from Andrew Howroyd, Apr 05 2021

Status

approved