A058534 A 3-way generalization of series-parallel networks with n unlabeled edges.

0, 1, 3, 6, 15, 36, 99, 270, 783, 2298, 6936, 21204, 65895, 206862, 656253, 2098602, 6761028, 21917364, 71450229, 234070806, 770216253, 2544458592, 8435990916, 28060099692, 93612265143, 313153860210, 1050194570445, 3530080085868

Offset

0,3

Comments

Compare the combstruct construction here with that for A000084.

Links

Table of n, a(n) for n=0..27.

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)} ]; [seq(combstruct[count](spec, size=n), n=0..40)]; # N = A058534, S=A000669

Crossrefs

Cf. A000084, A058540, A000669, A058561.

Sequence in context: A099323 A342912 A370241 * A063778 A279374 A087124

Adjacent sequences: A058531 A058532 A058533 * A058535 A058536 A058537

Keyword

nonn

Author

N. J. A. Sloane, Dec 24 2000

Status

approved