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A243394 Number of isomorphism classes of connected 3-regular multigraphs with n vertices and with loops and semi-edges allowed. 3
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

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

Table of n, a(n) for n=1..28.

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.

Sequence in context: A160820 A158357 A072953 * A175552 A279756 A103060

Adjacent sequences:  A243391 A243392 A243393 * A243395 A243396 A243397

KEYWORD

nonn

AUTHOR

Nico Van Cleemput, Jun 04 2014

EXTENSIONS

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

STATUS

approved

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Last modified October 21 21:51 EDT 2021. Contains 348155 sequences. (Running on oeis4.)