A085576 Array read by antidiagonals: T(n,k) = size of maximal subset of nodes in n X k grid such that there at least 3 edges between any pair of nodes (n >= 1, k >= 1).

1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 2, 3, 3, 4, 4, 4, 3, 3, 3, 4, 4, 5, 5, 4, 4, 3, 3, 4, 5, 6, 6, 6, 5, 4, 3, 4, 5, 6, 6, 7, 7, 6, 6, 5, 4, 4, 5, 6, 8, 8, 8, 8, 8, 6, 5, 4, 4, 6, 7, 8, 9, 9, 9, 9, 8, 7, 6, 4

Offset: 1

Author

N. J. A. Sloane, Jul 08 2003

Keywords

• nonn
• tabl

Comments

The 1-neighborhoods of the nodes must be disjoint: i.e. this is a 1-error correcting code.

Examples

			Array begins
1 1 1 2 2 2 3 3 3 4 ...
1 1 2 2 3 3 4 4 5 5 ...
1 2 2 3 4 4 5 6 6 7 ...
2 2 3 4 5 6 6 8 8 9 ...
For example, T(3,4) = 3 (*'s indicate the chosen nodes):
o--*--o--o
|..|..|..|
o--o--o--o
|..|..|..|
*--o--o--*
		

Crossrefs

Main diagonal gives A085577.

Formula

T(n, 1) = floor((n+2)/3), T(n, 2) = floor((n+1)/2).