A362894 Triangle read by rows: T(n,k) is the number of simple connected graphs on n unlabeled nodes having Hadwiger number k, 1 <= k <= n.

1, 0, 1, 0, 1, 1, 0, 2, 3, 1, 0, 3, 12, 5, 1, 0, 6, 50, 47, 8, 1, 0, 11, 230, 448, 152, 11, 1

Offset: 1

Author

Peter Kagey, May 08 2023

Keywords

• nonn
• tabl
• hard
• more

Comments

All planar graphs have Hadwiger number <= 4. The converse is not true since planar graphs also disallow a minor of K_{3,3}. - Andrew Howroyd, Jun 18 2025

Examples

			Triangle begins:
1;
0,  1;
0,  1,   1;
0,  2,   3,   1;
0,  3,  12,   5,   1;
0,  6,  50,  47,   8,  1;
0, 11, 230, 448, 152, 11, 1;
		

Links

• Eric Weisstein's World of Mathematics, Hadwiger Number
• Wikipedia, Hadwiger number

Crossrefs

Row sums are A001349.

Column 2 is A000055 for n > 1.

Subdiagonal is A024206.

Cf. A084269.

Cf. A032766 (n-cocktail party graph). A353212 (n-path complement graph).