A279452 Number of nonequivalent ways to place n points on an n X n square grid so that no more than 2 points are on a vertical or horizontal straight line.

1, 2, 14, 202, 4361, 126396, 4444935, 182567862, 8560638040, 451107721000

Offset

1,2

Comments

Rotations and reflections of placements are not counted. If they are to be counted, see A279444.

Links

Table of n, a(n) for n=1..10.

Example

There are a(3) = 14 nonequivalent ways to place 3 points on a 3 X 3 square grid under the condition mentioned above:
XX   XX.  XX.  XX.  XX.  XX.  X.X  X.X  X X  X..  X..  X..  .X.  .X.
..X  ...  X..  .X.  ...  ...  .X.  ...  ...  .XX  .X.  ..X  XX.  X.X
...  ..X  ...  ...  X..  .X.  ...  X..  .X.  ...  ..X  .X.  ...  ...

Crossrefs

Cf. A279444, A279453.

Sequence in context: A322196 A102224 A123543 * A262008 A054652 A122647

Adjacent sequences: A279449 A279450 A279451 * A279453 A279454 A279455

Keyword

nonn,more

Author

Heinrich Ludwig, Dec 23 2016

Status

approved