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 A141247 #5 Feb 16 2025 08:33:08
%S A141247 1,4,6,10,14,22,26,38,46,58,66,86,94,118,130,146,162,194,206,241,257,
%T A141247 282,302,346,362,401,426,462,486,542,558,609,641,690,722,770,794,861,
%U A141247 899,950,982,1062,1086,1157,1201,1258,1302,1393,1425,1501,1546,1613
%N A141247 Minimum number of points visible from a point in a square n X n lattice.
%C A141247 Two points (a,b) and (c,d) are visible to each other when gcd(c-a,d-b)=1. Sequence A141248 gives the number of lattice points that have minimal visibility.
%H A141247 T. D. Noe, <a href="/A141247/b141247.txt">Table of n, a(n) for n=1..1000</a>
%H A141247 Eric Weisstein, <a href="https://mathworld.wolfram.com/VisiblePoint.html">MathWorld: Visible Point</a>
%F A141247 The minimum number of visible points is slightly less than c*n^2, with c = 6/pi^2.
%t A141247 Table[mn=n^2+1; Do[cnt=0; Do[If[GCD[c-a,d-b]<2, cnt++ ], {a,n}, {b,n}]; If[cnt<mn, mn=cnt], {c,n}, {d,n}]; mn, {n,20}]
%Y A141247 Cf. A141224.
%K A141247 nonn
%O A141247 1,2
%A A141247 _T. D. Noe_, Jun 17 2008