A361446 - OEIS

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A361446

Number of connected 3-regular multigraphs on 2n unlabeled nodes rooted at an oriented edge (or loop), loops allowed.

1, 3, 16, 99, 717, 5964, 56701, 611750, 7432491, 100838222, 1514749135, 24989362186, 449429188211, 8754181791029, 183621843677724, 4126714250580949, 98932328702693666, 2520187379996442269, 67980528958530199837, 1935753445850303203221, 58025998739501873764826

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,2

COMMENTS

a(0) = 1 by convention. Loops add two to the degree of a node.

LINKS

Table of n, a(n) for n=0..20.

FORMULA

G.f.: B(x)/C(x) where B(x) is the g.f. of A352175 and C(x) is the g.f. of A129427.

CROSSREFS

A352174 is the 4-regular version.

Cf. A005967 (unrooted), A129427, A352175, A361412 (rooted at unoriented edge), A361447, A361448.