A291953 Number of unordered pairs of edge-disjoint trees on n labeled vertices.

1, 0, 0, 6, 570, 73620, 13675620, 3540401760, 1229855690952, 554518177819200, 315663337023994080, 221736991132524890880, 188570961922698640977120, 191056359142016559185938944, 227491517759156008014967128000

Offset

1,4

Links

Table of n, a(n) for n=1..15.

J. W. Moon, The second moment of the complexity of a graph, Mathematika 11:2 (1964), 95-98.

Formula

For n>1, a(n) = A291952(n)/2.

Crossrefs

Cf. A291952.

Sequence in context: A226263 A029590 A332156 * A225206 A268207 A268247

Adjacent sequences: A291950 A291951 A291952 * A291954 A291955 A291956

Keyword

nonn

Author

Max Alekseyev, Sep 06 2017

Status

approved