A046751 Triangle read by rows of number of connected graphs with n nodes and k edges (n >= 2, 1 <= k <= n(n-1)/2).

1, 0, 1, 1, 0, 0, 2, 2, 1, 1, 0, 0, 0, 3, 5, 5, 4, 2, 1, 1, 0, 0, 0, 0, 6, 13, 19, 22, 20, 14, 9, 5, 2, 1, 1, 0, 0, 0, 0, 0, 11, 33, 67, 107, 132, 138, 126, 95, 64, 40, 21, 10, 5, 2, 1, 1, 0, 0, 0, 0, 0, 0, 23, 89, 236, 486, 814, 1169, 1454, 1579, 1515, 1290, 970, 658, 400, 220, 114

Offset

2,7

Links

Table of n, a(n) for n=2..78.

G. A. Baker et al., High-temperature expansions for the spin-1/2 Heisenberg model, Phys. Rev., 164 (1967), 800-817.

Gordon Royle, Small graphs

Peter Steinbach, Field Guide to Simple Graphs, Volume 1, Part 17 (For Volumes 1, 2, 3, 4 of this book see A000088, A008406, A000055, A000664, respectively.)

Example

1;
0,1,1;
0,0,2,2,1, 1;
0,0,0,3,5, 5, 4, 2,  1,  1;
0,0,0,0,6,13,19,22, 20, 14,  9,  5, 2, 1, 1;
0,0,0,0,0,11,33,67,107,132,138,126,95,64,40,21,10,5,2,1,1;
[ the 4th row giving the numbers of connected graphs with 4 nodes and from 1 to 10 edges ].

Crossrefs

See A054924, which is the main entry for this triangle.

Cf. A002905, A008406, A046742, A054923, A054924.

Sequence in context: A049334 A054924 A370167 * A124478 A030353 A089617

Adjacent sequences: A046748 A046749 A046750 * A046752 A046753 A046754

Keyword

nonn,easy,nice,tabf

Author

N. J. A. Sloane

Extensions

More terms from Vladeta Jovovic, Apr 21 2000

Status

approved