

A235457


Number of nonequivalent (mod D_4) ways to arrange 6 points on an n X n square grid so that no three points are collinear.


6



1, 142, 4699, 77970, 672506, 4338248, 21167201, 85351595, 294664274, 911848844, 2528561187, 6501165477
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OFFSET

3,2


COMMENTS

Column 6 of A235453.
Without the restriction "nonequivalent (mod D_4)" the numbers are given by A194191, n >= 3.


LINKS

Table of n, a(n) for n=3..14.


EXAMPLE

There is a(3) = 1 way to place 6 points (X) on a 3 X 3 grid (without rotations and reflections):
. X X
X . X
X X .


CROSSREFS

Cf. A235453, A194191, A235454 (3 points), A235455 (4 points), A235456 (5 points), A235458 (7 points).
Sequence in context: A219146 A200453 A283638 * A200557 A077494 A217142
Adjacent sequences: A235454 A235455 A235456 * A235458 A235459 A235460


KEYWORD

nonn,more


AUTHOR

Heinrich Ludwig, Jan 12 2014


EXTENSIONS

a(13), a(14) from Heinrich Ludwig, Nov 16 2016


STATUS

approved



