A243394 Number of isomorphism classes of connected 3-regular multigraphs with n vertices and with loops and semi-edges allowed.

2, 5, 7, 22, 43, 141, 373, 1270, 4053, 14671, 52826, 203289, 795581, 3241367, 13504130, 57904671, 253856990, 1139231977, 5219113084, 24401837085, 116278408069, 564380686932, 2787884851040, 14007277302822, 71538337097031, 371197207327709, 1955833646495247, 10459788214042492

Offset: 1

Author

Nico Van Cleemput, Jun 04 2014

Keywords

• nonn

Comments

a(n) is also the number of isomorphism classes of connected multigraphs with n vertices of degree 3 or less and with loops allowed. - Andrew Howroyd, Mar 21 2020

Links

• G. Brinkmann, N. Van Cleemput, T. Pisanski, Generation of various classes of trivalent graphs, Theoretical Computer Science 502, 2013, pp.16-29.

Crossrefs

Cf. A000421, A005967, A243391, A243392, A243393, A243394.

Extensions

a(23)-a(28) from Andrew Howroyd, Mar 21 2020