OFFSET
1,6
LINKS
Keith M. Briggs, Combinatorial Graph Theory
EXAMPLE
Table of number of connected triangle-free graphs on n nodes with chromatic number k begins:
(The first row is the same as the number of connected bipartite graphs on n nodes, A005142)
n=...1...2...3...4...5....6....7.....8.....9.....10......11.......12.........13
k.-----------------------------------------------------------------------------
2|...0...1...1...3...5...17...44...182...730...4032...25598...212780....2241730 (A005142)
3|...0...0...0...0...1....2...15....85...650...5800...65243...931258...17182237 (the present sequence)
4|...0...0...0...0...0....0....0.....0.....0......0.......1.......23.......1085 (A126741)
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, based on email from Keith Briggs, Mar 21 2006
EXTENSIONS
a(14) from Michael Sollami, Jan 29 2012
a(15) from Michael Sollami, Feb 04 2012
STATUS
approved