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 A235454 Number of non-equivalent (mod D_4) ways to arrange 3 points on an n X n square grid so that they are not collinear. 6

%I

%S 1,13,70,290,867,2266,5068,10475,19764,35406,59817,97375,152154

%N Number of non-equivalent (mod D_4) ways to arrange 3 points on an n X n square grid so that they are not collinear.

%C Column 3 of A235453.

%C Also number of non-equivalent triangles in an n X n grid.

%C Without the restriction "non-equivalent (mod D_4)" the numbers are given by A045996, n >= 2.

%e There are a(3) = 13 non-equivalent ways to place 3 points on a 3 X 3 grid:

%e . . . . . . X . . . X . . . . . X . . X .

%e X . . X . . . . . . . . . X . X . X X X .

%e X X . X . X X . X X . X X . X . . . . . .

%e -

%e . . . . . . . . . . X . . X . . . X

%e X . X . X X X X . . . X X . . X . .

%e X . . X . . X . . X . . X . . X . .

%Y Cf. A235453, A045996, A235455 (4 points), A235456 (5 points), A235457 (6 points), A235458 (7 points).

%K nonn,more

%O 2,2

%A _Heinrich Ludwig_, Jan 12 2014

%E a(13), a(14) from _Heinrich Ludwig_, Nov 16 2016

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Last modified January 16 16:32 EST 2022. Contains 350376 sequences. (Running on oeis4.)