OFFSET
2,3
LINKS
R. C. Read, On the enumeration of a class of plane multigraphs, Aequat. Math., 31 (1986), 47-63.
FORMULA
Reference gives generating function.
CROSSREFS
KEYWORD
AUTHOR
EXTENSIONS
More terms from Pab Ter (pabrlos(AT)yahoo.com), May 27 2004
STATUS
approved