A357857 Number of (open and closed) trails in the complete undirected graph on n labeled vertices.

1, 4, 21, 232, 14425, 3653196, 17705858989, 261353065517776, 241809117107232026097

Offset

1,2

Comments

Trails are directed and pass through each (undirected) edge at most once in either of the two directions.

Links

Table of n, a(n) for n=1..9.

Formula

a(n) = n * A357855(n) + n * (n-1) * A357856(n).

Crossrefs

Cf. A007082, A135388, A232545, A350028, A356366, A357855, A357856, A357885, A357886, A357887.

Sequence in context: A286883 A217144 A132684 * A032074 A197662 A203218

Adjacent sequences: A357854 A357855 A357856 * A357858 A357859 A357860

Keyword

nonn,more,walk

Author

Max Alekseyev, Oct 16 2022

Extensions

a(9) from Bert Dobbelaere, Oct 17 2022

Status

approved