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A116079 Number of connected triangle-free graphs on n nodes with chromatic number 3. 3
0, 0, 0, 0, 1, 2, 15, 85, 650, 5800, 65243, 931258, 17182237, 414512599, 13161989059 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,6
LINKS
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: A108475 A328007 A098624 * A153445 A208974 A294196
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

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Last modified July 13 04:46 EDT 2024. Contains 374267 sequences. (Running on oeis4.)