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%I #7 Dec 24 2016 09:39:59
%S 2,6,54,1026,38931,2198241,167110761,16248457762,1960813221768
%N 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.
%C Row sum of triangle A279453.
%C Rotations and reflections of a placement are not counted. For numbers if they are to be counted, see A197458.
%Y Cf. A197458, A279453.
%K nonn,more
%O 1,1
%A _Heinrich Ludwig_, Dec 24 2016