A126732 Triangle read by rows: T(n,k) (n>=0, k=0..n) gives number of connected graphs on n nodes with edge chromatic number k.

1, 1, 0, 0, 1, 0, 0, 0, 1, 1, 0, 0, 2, 4, 0, 0, 0, 1, 8, 10, 2, 0, 0, 2, 26, 48, 36, 0, 0, 0, 1, 58, 279, 352, 159, 4, 0, 0, 2, 185, 1715, 4463, 3696, 1056, 0, 0, 0, 1, 500, 11464, 63363, 109760, 63605, 12378, 9, 0, 0, 2, 1677, 87114, 1066463, 3835747, 4541399, 1909444, 274725, 0

Offset

0,13

Links

Table of n, a(n) for n=0..65.

Keith M. Briggs, Combinatorial Graph Theory

Example

Triangle begins:
  n\k| 0  1  2    3     4       5       6       7       8      9 10
  ---+-------------------------------------------------------------
   0 | 1
   1 | 1  0
   2 | 0  1  0
   3 | 0  0  1    1
   4 | 0  0  2    4     0
   5 | 0  0  1    8    10       2
   6 | 0  0  2   26    48      36       0
   7 | 0  0  1   58   279     352     159       4
   8 | 0  0  2  185  1715    4463    3696    1056       0
   9 | 0  0  1  500 11464   63363  109760   63605   12378      9
  10 | 0  0  2 1677 87114 1066463 3835747 4541399 1909444 274725  0

Crossrefs

Cf. A001349 (row sums).

Sequence in context: A028573 A138758 A107501 * A371648 A347679 A028586

Adjacent sequences: A126729 A126730 A126731 * A126733 A126734 A126735

Keyword

nonn,tabl

Author

N. J. A. Sloane, Feb 16 2007

Status

approved