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A324217
Number of connected 2n-regular loopless multigraphs on seven unlabeled nodes.
4
0, 1, 50, 933, 12465, 119906, 864705, 4930446, 23280925, 94308983, 336704397, 1081565510, 3176476119, 8638660038, 21978039571, 52745266132, 120228555981, 261785061087, 547126506745, 1102086250237, 2147107495684
OFFSET
0,3
COMMENTS
There are no (2n+1)-regular graphs satisfying the condition above.
Multigraphs are loopless.
Initial terms computed with 'nauty and Traces' (see the link).
LINKS
Brendan McKay and Adolfo Piperno, nauty and Traces
PROG
(nauty/shell) for ((n=0; n<30; n=n+2)); do geng -c -d1 7 -q | multig -r${n} -u; done
CROSSREFS
Row n=7 of A328682.
Cf. A324218.
Sequence in context: A329713 A101929 A006360 * A224059 A224045 A224276
KEYWORD
nonn,more,hard
AUTHOR
Natan Arie Consigli, Apr 30 2019
EXTENSIONS
a(10)-a(20) from Andrew Howroyd, Mar 17 2020
STATUS
approved