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

1,2

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

Links

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

Example

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

Crossrefs

Cf. A049687, A049691, A124254, A300778.

Sequence in context: A255649 A209978 A294016 * A310912 A310913 A310914

Adjacent sequences: A344530 A344531 A344532 * A344534 A344535 A344536

Keyword

nonn

Author

John Mason, May 22 2021

Status

approved