A325474 Number of connected n-regular loopless multigraphs on eight unlabeled nodes.

0, 0, 1, 20, 204, 1689, 13303, 90614, 543116, 2842431, 13218770, 55233883, 210199115, 736166006, 2395665563, 7301022565, 20981692199, 57188601747, 148588072319, 369611918382, 883579452509, 2036672785494, 4539872512172, 9811474182969, 20605911433906, 42141179374995

Offset: 0

Author

Natan Arie Consigli, Aug 09 2019

Keywords

• nonn
• hard

Comments

Multigraphs are loopless.

Initial terms computed using 'Nauty and Traces' (see the link).

Links

• Andrew Howroyd, Table of n, a(n) for n = 0..30
• Brendan McKay and Adolfo Piperno, Nauty and Traces

Crossrefs

Row n=8 of A328682.

Cf. A324217, A324218.

Programs

nauty

for ((n=0;n<11;n++)); do geng -c -d1 8 -q | multig -r${n} -u; done

Extensions

Terms a(13) and beyond from Andrew Howroyd, Mar 17 2020