A129431 Number of isomorphism classes of 5-regular multigraphs of order 2n, loops allowed.

3, 32, 727, 42703, 5988679, 1639714425, 757559332934, 541249158493444, 564262722366313620, 822164422526588575949, 1618567795242262158194706, 4188563149202582371775198174, 13926836449718334345103644635724, 58360974360850795591633858610837541

Offset: 1

Author

Brendan McKay, Apr 15 2007

Keywords

• nonn

Comments

First seven terms were 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_, Oct 05 2009]

Crossrefs

Column k=5 of A167625.

Cf. A129430, A129420, A129427, A129429, A129433, A129435, A129437.

Formula

a(n) = N\{S_{2n}[S_5] * S_{5n}[S_2]\}. - Jason Kimberley, Oct 05 2009

Euler transform of A129430. - Andrew Howroyd, Mar 15 2020

Extensions

Using equation (5.8) of Read 1959, new terms a(8)-a(10) were computed in MAGMA during 2009 by Jason Kimberley, Dec 22 2010

a(11)-a(14) from Andrew Howroyd, Mar 21 2020