%I
%S 1,2,14,202,4361,126396,4444935,182567862,8560638040,451107721000
%N 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.
%C Rotations and reflections of placements are not counted. If they are to be counted, see A279444.
%e There are a(3) = 14 nonequivalent ways to place 3 points on a 3 X 3 square grid under the condition mentioned above:
%e XX XX. XX. XX. XX. XX. X.X X.X X X X.. X.. X.. .X. .X.
%e ..X ... X.. .X. ... ... .X. ... ... .XX .X. ..X XX. X.X
%e ... ..X ... ... X.. .X. ... X.. .X. ... ..X .X. ... ...
%Y Cf. A279444, A279453.
%K nonn,more
%O 1,2
%A _Heinrich Ludwig_, Dec 23 2016
