A344533 - OEIS

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.

%I #24 May 26 2021 05:15:01

%S 1,4,7,14,17,30,33,52,51,82,81,108,105,156,143,198,183,252,231,308,

%T 267,380,339,436,383,526,461,598,525,680,595,782,663,896,767,974,839,

%U 1118,953,1208,1041,1330,1143,1466,1227,1620,1383,1738,1473,1898,1605,2034

%N 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.

%C 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

%H John Mason, <a href="/A344533/b344533.txt">Table of n, a(n) for n = 1..10000</a>

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

%Y Cf. A049687, A049691, A124254, A300778.

%K nonn

%O 1,2

%A _John Mason_, May 22 2021