login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A129429 Number of isomorphism classes of 4-regular multigraphs of order n, loops allowed. 13
1, 3, 7, 20, 56, 187, 654, 2705, 12587, 67902, 417065, 2897432, 22382255, 189930004, 1750561160, 17380043136, 184653542135, 2088649831822, 25046462480066, 317295911519901, 4233450347175663, 59329632953577985, 871281036897298464 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
Initial terms computed using software at http://users.cecs.anu.edu.au/~bdm/nauty/
Equation (5.8) of Read's paper tells us a(n) = N {S_n[S_4] * S_{2n}[S_2]}, where we are working with cycle index polynomials. - Jason Kimberley, Oct 05 2009
LINKS
R. de Mello Koch and S. Ramgoolam, Strings from Feynman graph counting: Without large N, Phys. Rev. D 85 (2012) 026007
R. C. Read, The enumeration of locally restricted graphs (I), J. London Math. Soc. 34 (1959) 417-436.
FORMULA
Euler transform of A085549. - Andrew Howroyd, Mar 15 2020
CROSSREFS
Column k=4 of A167625.
Sequence in context: A058737 A274478 A238124 * A084204 A030238 A132364
KEYWORD
nonn
AUTHOR
Brendan McKay, Apr 15 2007
EXTENSIONS
Using equation (5.8) of Read's paper, new terms a(17)-a(19) were computed in MAGMA by Jason Kimberley, Oct 05 2009
Four more terms a(20)-a(23) also computed by Jason Kimberley, Nov 09 2009
STATUS
approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 28 05:02 EDT 2024. Contains 371235 sequences. (Running on oeis4.)