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 A126749 Triangle read by rows: T(n,k) (n>=2, k=0..n-1) gives number of biconnected graphs on n nodes with chromatic number n-k. 5
 0, 1, 0, 1, 1, 1, 1, 2, 6, 1, 1, 3, 17, 30, 5, 1, 4, 34, 189, 232, 8, 1, 5, 59, 627, 3627, 2762, 42, 1, 6, 92, 1631, 23262, 118114, 50814, 146, 1, 7, 135, 3643, 101409, 1686975, 6530233, 1420183, 956 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 2,8 COMMENTS It is possible that the definition should say "connected" rather than "biconnected". Should be rechecked! - Max Alekseyev and Brendan McKay, Jun 17 2008 LINKS Keith M. Briggs, Combinatorial Graph Theory EXAMPLE Triangle begins: n=...1..2...3...4...5....6.....7......8........9........10 k.--------------------------------------------------------- 2|...0..0...0...1...1....5.....8.....42......146.......956 3|...0..0...1...1...6...30...232...2762....50814...1420183 4|...0..0...0...1...2...17...189...3627...118114...6530233 5|...0..0...0...0...1....3....34....627....23262...1686975 6|...0..0...0...0...0....1.....4.....59.....1631....101409 7|...0..0...0...0...0....0.....1......5.......92......3643 8|...0..0...0...0...0....0.....0......1........6.......135 CROSSREFS Diagonals give A126750-A126754. Sequence in context: A065529 A205015 A204937 * A024573 A191359 A289203 Adjacent sequences:  A126746 A126747 A126748 * A126750 A126751 A126752 KEYWORD nonn,tabl,more AUTHOR N. J. A. Sloane, Feb 18 2007 STATUS approved

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Last modified September 20 22:20 EDT 2019. Contains 327252 sequences. (Running on oeis4.)