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A361446
Number of connected 3-regular multigraphs on 2n unlabeled nodes rooted at an oriented edge (or loop), loops allowed.
3
1, 3, 16, 99, 717, 5964, 56701, 611750, 7432491, 100838222, 1514749135, 24989362186, 449429188211, 8754181791029, 183621843677724, 4126714250580949, 98932328702693666, 2520187379996442269, 67980528958530199837, 1935753445850303203221, 58025998739501873764826
OFFSET
0,2
COMMENTS
a(0) = 1 by convention. Loops add two to the degree of a node.
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.
Sequence in context: A193037 A363573 A246056 * A360638 A091641 A137572
KEYWORD
nonn
AUTHOR
Andrew Howroyd, Mar 12 2023
STATUS
approved