1,6

Keith M. Briggs, Combinatorial Graph Theory

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)

Adjacent sequences: A116076 A116077 A116078 this_sequence A116080 A116081 A116082

Sequence in context: A002740 A108475 A098624 this_sequence A037746 A037627 A037753

nonn

njas, based on email from Keith M. Briggs, Mar 21 2006