A360871 Number of unlabeled nonseparable (or 2-connected) multigraphs with n edges and degree >= 3 at each node, loops allowed.

0, 0, 2, 4, 9, 20, 44, 113, 329, 1044, 3622, 13544, 53596, 223084, 969158

Offset

1,3

Comments

A single-edge is considered to be nonseparable here.

Links

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

Example

The a(3) = 2 multigraphs are:
  - a triple edge;
  - a single edge with a loop at each vertex.

Crossrefs

Row sums of A360870.

Cf. A002935, A360863, A360867.

Sequence in context: A024562 A087219 A214952 * A199296 A219229 A091620

Adjacent sequences: A360868 A360869 A360870 * A360872 A360873 A360874

Keyword

nonn,more

Author

Andrew Howroyd, Feb 25 2023

Status

approved