A129417 Number of isomorphism classes of connected 4-regular loopless multigraphs of order n.

1, 0, 1, 1, 3, 6, 19, 50, 204, 832, 4330, 25227, 171886, 1303725, 10959478, 100230117, 989280132, 10455393155, 117701173970, 1405165683359, 17726785643045, 235585551038117, 3289367315407521, 48136794098893837, 736721822918719557, 11768987500655142988

Offset

0,5

Comments

Initial terms computed using software at http://users.cecs.anu.edu.au/~bdm/nauty/

Obtained from A129418 by an inverse Euler transform. - R. J. Mathar, Mar 09 2019

Links

Table of n, a(n) for n=0..25.

Brendan McKay and Adolfo Piperno, Nauty and Traces

Prog

(nauty/bash) geng -c -d1 ${n} -q | multig -r4 -u # Natan Arie Consigli, Jun 05 2017

Crossrefs

Column k=4 of A328682.

Cf. A129418, A085549, A000421, A129419, A129421, A129423, A129425, A328682.

Sequence in context: A148568 A003162 A179277 * A369553 A132335 A148569

Adjacent sequences: A129414 A129415 A129416 * A129418 A129419 A129420

Keyword

nonn

Author

Brendan McKay, Apr 15 2007

Extensions

a(0)-a(1) prepended by Natan Arie Consigli, Jun 05 2017

a(18)-a(25) from Andrew Howroyd, Mar 17 2020

Status

approved