OFFSET
1,4
COMMENTS
The paw graph and square graph C_4 on 4 have common Wiener index 8, while all other connected simple graphs on 4 nodes have unique Wiener indices, so a(4) = 2.
LINKS
Eric Weisstein's World of Mathematics, Wiener Index
CROSSREFS
KEYWORD
nonn,hard,more
AUTHOR
Eric W. Weisstein, Jul 18 2011
STATUS
approved