login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
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

Table of n, a(n) for n=2..46.

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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

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