

A361135


The number of unlabeled connected fairly 4regular multigraphs of order n, loops allowed.


5



1, 3, 8, 30, 118, 548, 2790, 16029, 101353, 706572, 5375249, 44402094, 395734706, 3786401086, 38711834576, 421217184135, 4860174299186, 59278045511959, 762055884150141, 10299293881159294, 145994591873294780, 2165938721141964179, 33564939201581495090, 542344644703485899950, 9122110321170144880053
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OFFSET

1,2


COMMENTS

Edges are undirected, vertices not labeled. "Fairly" means that each vertex has degree 4, but two of these edges do not connect to a second vertex; they are "fins" in CAD speak or "halfedges" in perturbation theory. The two fins may be attached to the same or to two different nodes. In the usual mathematical nomenclature these are connected graphs of order n+2 with two vertices of degree 1 and n vertices of degree 4, loops allowed.


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CROSSREFS



KEYWORD

nonn,hard


AUTHOR



EXTENSIONS



STATUS

approved



