A344533 Given a square forest of n X n trees, with rows and columns separated by 1 meter, a(n) is the number of trees visible to an observer halfway along one side of the forest, exactly one meter outside.

1, 4, 7, 14, 17, 30, 33, 52, 51, 82, 81, 108, 105, 156, 143, 198, 183, 252, 231, 308, 267, 380, 339, 436, 383, 526, 461, 598, 525, 680, 595, 782, 663, 896, 767, 974, 839, 1118, 953, 1208, 1041, 1330, 1143, 1466, 1227, 1620, 1383, 1738, 1473, 1898, 1605, 2034

Offset: 1

Author

John Mason, May 22 2021

Keywords

• nonn

Comments

This concept has been studied under the name "visible lattice points" although the usual version considers the points in an n X n grid that are visible from the origin. - Jeffrey Shallit, May 22 2021

Examples

			For example, if the forest contains 5 X 5 trees, the observer will see only 17, as 8 will be hidden.
		

Links

• John Mason, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A049687, A049691, A124254, A300778.