A165164 Smallest k such that no set of n lattice points gives visibility to every point of a square k X k lattice.

4, 6, 24, 133

Offset: 1

Author

Jon E. Schoenfield, Sep 06 2009

Keywords

• hard
• nonn

Comments

At least n+1 lattice points must be selected as viewpoints in order to give visibility to all lattice points of a square a(n) X a(n) lattice.

Examples

			For k < 24, given a k X k square lattice, there is at least one way to select a set of 3 or fewer lattice points as viewpoints that, collectively, give visibility to all k^2 lattice points; at k=24, however, no such set of 3 points exists, so a(3)=24.
		

Crossrefs

Equals minimum k such that A157639(k) > n.