OFFSET
1,4
LINKS
Sebastian Jeon, Tanya Khovanova, 3-Symmetric Graphs, arXiv:2003.03870 [math.CO], 2020.
EXAMPLE
a(1) = 1: There is 1 graph with 1 node and 0 edges.
a(2) = 0: There are no graphs with 2 nodes 1/2 edges. (More generally, if n = 2 or 3 mod 4 then a(n) = 0.)
a(4) = 3: There are 3 graphs with 4 nodes and 3 edges.
a(5) = 6: There are 6 graphs with 5 nodes and 5 edges.
a(8) = 1646: There are 1646 graphs with 8 nodes and 28 edges.
a(9) = 34040: There are 34040 graphs with 9 nodes and 36 edges.
MATHEMATICA
Needs["Combinatorica`"]; Array[If[Mod[#, 4] == 1 || Mod[#, 4] == 0, NumberOfGraphs[#, # (# - 1)/4], 0] &, 25]
CROSSREFS
KEYWORD
nonn
AUTHOR
Geoffrey Critzer, Oct 20 2012
EXTENSIONS
Mathematica corrected by Michael De Vlieger, Jun 17 2020
STATUS
approved