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).

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

Table of n, a(n) for n=1..25.

A. Flammenkamp, Solutions of the no-three-in-line problem

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: A211365 A346498 A213135 * A248061 A267500 A355785

Adjacent sequences: A037184 A037185 A037186 * A037188 A037189 A037190

Keyword

nonn,more

Author

N. J. A. Sloane.

Extensions

There are published versions of this sequence which incorrectly give 693 instead of 675.

Status

approved