A324217 Number of connected 2n-regular loopless multigraphs on seven unlabeled nodes.

0, 1, 50, 933, 12465, 119906, 864705, 4930446, 23280925, 94308983, 336704397, 1081565510, 3176476119, 8638660038, 21978039571, 52745266132, 120228555981, 261785061087, 547126506745, 1102086250237, 2147107495684

Offset: 0

Author

Natan Arie Consigli, Apr 30 2019

Keywords

• nonn
• more
• hard

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

Crossrefs

Row n=7 of A328682.

Cf. A324218.

Programs

nauty

for ((n=0;n<30;n=n+2)); do geng -c -d1 7 -q | multig -r${n} -u; done

Extensions

a(10)-a(20) from Andrew Howroyd, Mar 17 2020