OFFSET
0,11
LINKS
EXAMPLE
a(0)=0 because even though the null graph (on zero vertices) is vacuously 4-regular and connected, since it is acyclic, it has infinite girth.
The a(8)=1 graph is the complete bipartite graph K_{4,4}.
CROSSREFS
4-regular simple graphs with girth exactly 4: this sequence (connected), A185044 (disconnected), A185144 (not necessarily connected).
Connected k-regular simple graphs with girth exactly 4: A006924 (k=3), this sequence (k=4), A184954 (k=5), A184964 (k=6), A184974 (k=7).
Connected 4-regular simple graphs with girth at least g: A006820 (g=3), A033886 (g=4), A058343 (g=5), A058348 (g=6).
KEYWORD
nonn,hard,more
AUTHOR
Jason Kimberley, Jan 26 2011
EXTENSIONS
a(23) was appended by the author once A033886(23) was known, Nov 03 2011
STATUS
approved