A123850 Triangle read by rows: T(n,k) = orientable embedding number gamma_k for bouquet B_n, n >= 0, 0 <= k <= [n/2].

1, 1, 4, 2, 40, 80, 672, 3360, 1008, 16128, 161280, 185472

Offset

0,3

References

Jonathan L. Gross and Thomas W. Tucker, Enumerating graph embeddings and partial-duals by genus and Euler genus, ECA 1:1 (2021) Article S2S1. See Table 1. (Beware errors!)

J. L. Gross and J. Yellen, eds., Handbook of Graph Theory, CRC Press, 2004; p. 649.

Links

Table of n, a(n) for n=0..11.

Formula

Reference gives a recurrence.

Example

Triangle begins:
1
1
4 2
40 80
672 3360 1008
16128 161280 185472

Crossrefs

Columns give A005431, A123828. Row sums are (2n-1)1.

Sequence in context: A302890 A307974 A303625 * A280780 A264755 A120968

Adjacent sequences: A123847 A123848 A123849 * A123851 A123852 A123853

Keyword

nonn,tabf,more

Author

N. J. A. Sloane, Nov 19 2006

Status

approved