A181946 Number of kites, distinct up to congruence, on an n X n grid (or geoboard).

0, 1, 4, 11, 25, 45, 81, 121, 188, 261, 368, 469, 641, 785, 1000, 1220, 1520, 1767, 2161, 2471, 2961, 3396, 3946, 4403, 5164, 5744, 6517, 7227, 8201, 8936, 10122, 10963, 12240, 13312, 14649, 15839, 17607, 18813, 20482, 21983, 24111, 25589, 27920, 29550, 31979

Offset: 1

Author

Martin Renner, Apr 03 2012

Keywords

• nonn

Comments

Only convex kites are counted, not concave kites (sometimes called darts or arrowheads).

Examples

			a(1) = 0 because the 1 X 1 grid has no kites.
a(2) = 1 because the 2 X 2 grid has one kite.
a(3) = 4 because the 3 X 3 grid has 4 congruence classes of kites, out of 10 kites total:
+-------+-------+-------+-------+
| . . . | o . o | . . o | . o . |
| o o . | . . . | o . . | o . o |
| o o . | o . o | o o . | . o . |
+-------+-------+-------+-------+
		

Links

• Lucas A. Brown, Python program.
• Eric Weisstein's World of Mathematics, Kite.

Crossrefs

Cf. A181944, A189417.

Extensions

a(7)-a(45) from Lucas A. Brown, Feb 08 2024