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

1,2

Comments

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

Links

Table of n, a(n) for n=1..18.

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

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

Crossrefs

Column k=8 of A167625.

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

Sequence in context: A121942 A006294 A239982 * A048252 A356773 A208804

Adjacent sequences: A129434 A129435 A129436 * A129438 A129439 A129440

Keyword

nonn

Author

Brendan McKay, Apr 15 2007

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

Status

approved