A129421 Number of isomorphism classes of connected 6-regular loopless multigraphs of order n.

0, 1, 1, 6, 15, 120, 933, 13303, 252207, 6450828, 205475039, 7936493756, 363639228194, 19476976825809, 1205115679461426, 85288127619421544, 6845235025444882069, 618411485467843477405, 62471139399366989007575, 7014991719815977343879171

Offset

1,4

Comments

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

Links

Table of n, a(n) for n=1..20.

Brendan McKay and Adolfo Piperno, Nauty and Traces

Formula

Inverse Euler transform of A129422. - Andrew Howroyd, Mar 17 2020

Prog

(nauty/bash) geng -c -d1 ${n} -q | multig -r6 -u # Natan Arie Consigli, Jun 05 2017

Crossrefs

Column k=6 of A328682.

Cf. A129422, A129432, A000421, A129417, A129419, A129423, A129425, A328682.

Sequence in context: A219771 A087137 A056317 * A013227 A013223 A219289

Adjacent sequences: A129418 A129419 A129420 * A129422 A129423 A129424

Keyword

nonn

Author

Brendan McKay, Apr 15 2007

Extensions

a(1)=0 prepended and a(14)-a(20) from Andrew Howroyd, Mar 17 2020

Status

approved