A129437 Number of isomorphism classes of 8-regular multigraphs of order n, loops allowed.

1, 5, 22, 181, 2183, 47773, 1689841, 90972682, 6948008975, 721121538707, 98626660242232, 17361164959413148, 3857920886847174328, 1064590883337392451345, 359664321908847682542521, 146924560811224485478212220, 71778969194383385732028947007, 41528817306107485906955040499799

Offset: 1

Author

Brendan McKay, Apr 15 2007

Keywords

• nonn

Comments

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

Links

• R. C. Read, The enumeration of locally restricted graphs (I), J. London Math. Soc. 34 (1959) 417-436. [From _Jason Kimberley_, Nov 09 2009]

Crossrefs

Column k=8 of A167625.

Cf. A129436, A129426, A129427, A129429, A129431, A129433, A129435.

Formula

a(n)=N\{S_n[S_8] * S_{4n}[S_2]\}. - Jason Kimberley, Nov 09 2009

Euler transform of A129436. - Andrew Howroyd, Mar 15 2020

Extensions

Using equation (5.8) of Read 1959, McKay's terms verified by, and new term a(11) was computed by Jason Kimberley, Nov 09 2009

a(12)=N{S_12[S_8]*S_48[S_2]} was computed in MAGMA, on one processor of ARCSgrid at UNcle, using 17 GB virtual memory, over 49 real days, with 36 days processor time, by Jason Kimberley, Nov 29 2009

a(13)-a(18) from Andrew Howroyd, Mar 21 2020