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A235458 Number of non-equivalent (mod D_4) ways to arrange 7 points on an n X n square grid so that no three points are collinear. 6
28, 3385, 134353, 1958674, 19929645, 138586349, 753795278, 3356614240, 13108210508, 44374441652, 137349454120 (list; graph; refs; listen; history; text; internal format)
OFFSET

4,1

COMMENTS

Column 7 of A235453.

Without the restriction "non-equivalent (mod D_4)" the numbers are given by A194192, n >= 4.

LINKS

Table of n, a(n) for n=4..14.

EXAMPLE

There are a(4) = 28 non-equivalent ways to place 7 points (X) on a 4 X 4 grid. Example:

   . X X .

   . . . X

   X . . X

   X X . .

CROSSREFS

Cf. A235453, A194192, A235454 (3 points), A235455 (4 points), A235456 (5 points), A235457 (6 points).

Sequence in context: A285151 A232520 A061787 * A128506 A164655 A291585

Adjacent sequences:  A235455 A235456 A235457 * A235459 A235460 A235461

KEYWORD

nonn,more

AUTHOR

Heinrich Ludwig, Jan 12 2014

EXTENSIONS

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

STATUS

approved

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Last modified September 28 04:24 EDT 2021. Contains 347698 sequences. (Running on oeis4.)