OFFSET
1,13
REFERENCES
A. A. Dobrynin (dobr(AT)math.nsc.ru), Distance of iterated line graphs, Graph Theory Notes of NY, 37 (1999), 8-9.
LINKS
A. A. Dobrynin and L. S. Mel'nikov, Some results on the Wiener index of iterated line graphs, Electronic Notes in Discrete Mathematics 22 (2005), 469-475
PROG
(Sage) # needs the package nauty
def a(n):
c = 0
for el in graphs.nauty_geng(str(n) + ' -c ' + str(n-1)+':' + str(n-1)):
g = (el.line_graph()).line_graph()
if el.wiener_index() == g.wiener_index():
c+=1
return c
# Jernej Azarija, Aug 13 2012
CROSSREFS
KEYWORD
nonn
AUTHOR
EXTENSIONS
More terms (from Dobrynin/Mel'nikov reference), Jernej Azarija, Aug 13 2012
STATUS
approved