A058540 Another 3-way generalization of series-parallel networks with n unlabeled edges.

0, 1, 3, 9, 36, 144, 651, 3015, 14634, 72654, 369063, 1904985, 9971889, 52788393, 282161025, 1520597895, 8253281871, 45075359277, 247534382298, 1365994896264, 7571065357620, 42127865408028, 235246997219400, 1317894484506336

Offset

0,3

Comments

Compare the combstruct construction here with those for A000084 and A058534.

Links

Table of n, a(n) for n=0..23.

Maple

spec := [ N, {N=Union(Z, S, P, Q), S=Set(Union(Z, P, Q), card>=2), P=Set(Union(Z, S, Q), card>=2), Q=Set(Union(Z, S, P), card>=2)} ]; [seq(combstruct[count](spec, size=n), n=0..40)]; # N=A058540, S=A058371

Crossrefs

Cf. A000084, A058534, A058371.

Sequence in context: A185162 A106435 A276368 * A350451 A245888 A379034

Adjacent sequences: A058537 A058538 A058539 * A058541 A058542 A058543

Keyword

nonn

Author

N. J. A. Sloane, Dec 24 2000

Status

approved