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

Author

Max Alekseyev, Oct 16 2022

Keywords

• nonn
• more
• walk

Comments

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

Crossrefs

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

Formula

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

Extensions

a(9) from Bert Dobbelaere, Oct 17 2022