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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. 7
1, 2, 14, 202, 4361, 126396, 4444935, 182567862, 8560638040, 451107721000 (list; graph; refs; listen; history; text; internal format)
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

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Last modified August 9 01:35 EDT 2020. Contains 336310 sequences. (Running on oeis4.)