A358243 Number of n-regular, N_0-weighted pseudographs on 2 vertices with total edge weight 3, up to isomorphism.

1, 4, 9, 15, 21, 28, 34, 41, 47, 54, 60, 67, 73, 80, 86, 93, 99, 106, 112, 119, 125, 132, 138, 145, 151, 158, 164, 171, 177, 184, 190, 197, 203, 210, 216, 223, 229, 236, 242, 249, 255, 262, 268, 275, 281, 288, 294, 301, 307, 314, 320, 327, 333, 340, 346, 353

Offset: 1

Author

Lars Göttgens, Nov 04 2022

Keywords

• nonn

Comments

Pseudographs are finite graphs with undirected edges without identity, where parallel edges between the same vertices and loops are allowed.

Crossrefs

Other total edge weights 4 (A358244), 5 (A358245), 6 (A358246), 7 (A358247), 8 (A358248), 9 (A358249).

Cf. A258589.

Formula

Apparently a(n) = A258589(n-2) + 2 for n>= 4, i.e., terms satisfy linear recurrence a(n) = a(n-1) + a(n-2) - a(n-3) for n>=7. - Hugo Pfoertner, Dec 02 2022