This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A344533 #24 May 26 2021 05:15:01 %S A344533 1,4,7,14,17,30,33,52,51,82,81,108,105,156,143,198,183,252,231,308, %T A344533 267,380,339,436,383,526,461,598,525,680,595,782,663,896,767,974,839, %U A344533 1118,953,1208,1041,1330,1143,1466,1227,1620,1383,1738,1473,1898,1605,2034 %N 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. %C A344533 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 A344533 John Mason, <a href="/A344533/b344533.txt">Table of n, a(n) for n = 1..10000</a> %e A344533 For example, if the forest contains 5 X 5 trees, the observer will see only 17, as 8 will be hidden. %Y A344533 Cf. A049687, A049691, A124254, A300778. %K A344533 nonn %O A344533 1,2 %A A344533 _John Mason_, May 22 2021