|
| |
|
|
A058561
|
|
A 3-way generalization of series-parallel networks with n labeled edges.
|
|
2
| |
|
|
0, 1, 3, 12, 78, 708, 8256, 117624, 1980096, 38456736, 846413472, 20819693568, 565998548352, 16852047061632, 545372109629184, 19061178127458816, 715541912895773184, 28713061759257037824, 1226513716981332031488
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 0,3
|
|
|
MAPLE
| spec := [ N, {N=Union(Z, S, P, Q), S=Set(Union(Z, P), card>=2), P=Set(Union(Z, Q), card>=2), Q=Set(Union(Z, S), card>=2)}, labeled ]; [seq(combstruct[count](spec, size=n), n=0..40)]; # N = A058561, S=A000311
|
|
|
CROSSREFS
| Cf. A058534, A000311, A006351.
Sequence in context: A060946 A121421 A108043 * A058107 A023879 A084565
Adjacent sequences: A058558 A058559 A058560 * A058562 A058563 A058564
|
|
|
KEYWORD
| nonn
|
|
|
AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), Dec 26 2000
|
| |
|
|
