1,1

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.

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.

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

Sequence in context: A057343 A000287 A032087 this_sequence A136591 A009459 A123055

Adjacent sequences: A165161 A165162 A165163 this_sequence A165165 A165166 A165167

hard,nonn

Jon E. Schoenfield (jonscho(AT)hiwaay.net), Sep 06 2009