A126732 - OEIS

%I #11 Apr 02 2024 14:33:45

%S 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,

%T 279,352,159,4,0,0,2,185,1715,4463,3696,1056,0,0,0,1,500,11464,63363,

%U 109760,63605,12378,9,0,0,2,1677,87114,1066463,3835747,4541399,1909444,274725,0

%N 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.

%H Keith M. Briggs, <a href="http://keithbriggs.info/cgt.html">Combinatorial Graph Theory</a>

%e Triangle begins:

%e   n\k| 0  1  2    3     4       5       6       7       8      9 10

%e   ---+-------------------------------------------------------------

%e    0 | 1

%e    1 | 1  0

%e    2 | 0  1  0

%e    3 | 0  0  1    1

%e    4 | 0  0  2    4     0

%e    5 | 0  0  1    8    10       2

%e    6 | 0  0  2   26    48      36       0

%e    7 | 0  0  1   58   279     352     159       4

%e    8 | 0  0  2  185  1715    4463    3696    1056       0

%e    9 | 0  0  1  500 11464   63363  109760   63605   12378      9

%e   10 | 0  0  2 1677 87114 1066463 3835747 4541399 1909444 274725  0

%Y Cf. A001349 (row sums).

%K nonn,tabl

%O 0,13

%A _N. J. A. Sloane_, Feb 16 2007