A116079 - OEIS

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A116079

Number of connected triangle-free graphs on n nodes with chromatic number 3.

0, 0, 0, 0, 1, 2, 15, 85, 650, 5800, 65243, 931258, 17182237, 414512599, 13161989059 (list; graph; refs; listen; history; internal format)

	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	`Sequence in context: A178750 A108475 A098624 * A153445 A037746 A037627` `Adjacent sequences: A116076 A116077 A116078 * A116080 A116081 A116082`
	KEYWORD	`nonn,changed`
	AUTHOR	`N. J. A. Sloane (njas(AT)research.att.com), based on email from Keith M. Briggs, Mar 21 2006`
	EXTENSIONS	`a(14) from Michael Sollami, Jan 29 2012.` `a(15) from Michael Sollami, Feb 04 2012.`

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Last modified February 15 20:03 EST 2012. Contains 205852 sequences.