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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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,6

REFERENCES

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.

LINKS

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

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

CROSSREFS

Cf. A000769.

Sequence in context: A082225 A211365 A213135 * A166542 A189711 A092939

Adjacent sequences:  A037184 A037185 A037186 * A037188 A037189 A037190

KEYWORD

nonn

AUTHOR

N. J. A. Sloane.

EXTENSIONS

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

STATUS

approved

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Last modified December 20 09:43 EST 2014. Contains 252241 sequences.