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A037187
Number of ways of placing 2n points on n X n grid so no 3 are in a line (solutions with 180 deg rotational symmetry).
1
0, 0, 0, 1, 0, 2, 10, 7, 7, 13, 30, 33, 82, 61, 283, 189, 282, 328, 594, 675, 2413, 1248, 3968, 2852, 8983
OFFSET
1,6
LINKS
A. Flammenkamp, Progress in the no-three-in-line problem, J. Combinat. Theory A 60 (1992), 305-311.
A. Flammenkamp, Progress in the no-three-in-line problem. II, J. Combin. Theory Ser. A 81 (1998), no. 1, 108-113.
CROSSREFS
Cf. A000769.
Sequence in context: A346498 A376376 A213135 * A248061 A267500 A355785
KEYWORD
nonn,more
AUTHOR
EXTENSIONS
There are published versions of this sequence which incorrectly give 693 instead of 675.
STATUS
approved