OFFSET
0,3
REFERENCES
R. C. Read and R. J. Wilson, An Atlas of Graphs, Oxford, 1998.
LINKS
Andrew Howroyd, Table of n, a(n) for n = 0..50
Wikipedia, Signed graph
FORMULA
Euler transform of A318590.
CROSSREFS
KEYWORD
nonn,nice
AUTHOR
Ronald C. Read
EXTENSIONS
Name clarified and offset corrected by Andrew Howroyd, Sep 25 2018
a(0)=1 prepended and terms a(13) and beyond from Andrew Howroyd, Sep 25 2018
STATUS
approved