A327604 Number of connected 2n-regular loopless multigraphs on nine unlabeled nodes.

0, 1, 832, 252207, 35241608, 2351580473, 89216898630, 2194653376016, 38376657658125, 509484171323720, 5390386822995890, 47150458233195944, 350827631527584993, 2271025998493100911, 13023793690772493636

Offset: 0

Author

Natan Arie Consigli, Sep 18 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=9 of A328682.

Cf. A324217, A324218.

Programs

nauty

for ((n=0;n<12;n=n+2)); do geng -c -d1 9 -q | multig -r${n} -u; done

Extensions

a(6)-a(14) from Andrew Howroyd, Mar 18 2020