A279454 Number of nonequivalent ways to place k>=0 points on an n X n square grid so that no more than 2 points are on a vertical or horizontal straight line.

2, 6, 54, 1026, 38931, 2198241, 167110761, 16248457762, 1960813221768

Offset: 1

Author

Heinrich Ludwig, Dec 24 2016

Keywords

• nonn
• more

Comments

Row sum of triangle A279453.

Rotations and reflections of a placement are not counted. For numbers if they are to be counted, see A197458.

Crossrefs

Cf. A197458, A279453.