

A165627


Number of 6regular graphs (sextic graphs) on n vertices.


12



1, 0, 0, 0, 0, 0, 0, 1, 1, 4, 21, 266, 7849, 367860, 21609301, 1470293676, 113314233813, 9799685588961
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

0,10


COMMENTS

Because the triangle A051031 is symmetric, a(n) is also the number of (n7)regular graphs on n vertices.


REFERENCES

M. Meringer, Fast Generation of Regular Graphs and Construction of Cages. Journal of Graph Theory, 30 (1999), 137146.


LINKS

Table of n, a(n) for n=0..17.
Jason Kimberley, Index of sequences counting not necessarily connected kregular simple graphs with girth at least g
M. Meringer, Tables of Regular Graphs
N. J. A. Sloane, Transforms
Eric Weisstein's World of Mathematics, Regular Graph
Eric Weisstein's World of Mathematics, Sextic Graph


FORMULA

Euler transformation of A006822.


CROSSREFS

6regular simple graphs: A006822 (connected), A165656 (disconnected), this sequence (not necessarily connected).
Regular graphs A005176 (any degree), A051031 (triangular array), chosen degrees: A000012 (k=0), A059841 (k=1), A008483 (k=2), A005638 (k=3), A033301 (k=4), A165626 (k=5), this sequence (k=6), A165628 (k=7), A180260 (k=8).
Sequence in context: A185163 A184961 A006822 * A198050 A270482 A126458
Adjacent sequences: A165624 A165625 A165626 * A165628 A165629 A165630


KEYWORD

nonn,hard,more


AUTHOR

Jason Kimberley, Sep 22 2009


EXTENSIONS

Crossreferences edited by the author, Nov 07 2009 and Oct 17 2011.
The author appended a(17) on Dec 30 2010.


STATUS

approved



