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 A071339 #11 Jul 14 2024 03:51:12 %S A071339 1,4,4,8,8,12,12,12,12,16,16,16,16,16,16,16,16,16,16,24,24,24,24,24, %T A071339 24,24,24,24,24,24,24,24,24,24,32,32,32,32,32,32,32,32,32,32,32,32,32, %U A071339 32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,36,36,36 %N A071339 a(n) = the maximum number of lattice points touched by an origin-centered circle with radius <= n. %H A071339 Hugo Pfoertner, <a href="https://www.randomwalk.de/sequences/a071339.txt">FORTRAN program for A071339-A071347</a> %F A071339 a(n) = max(i=0 to n^2) A004018(i) %e A071339 a(5 to 8)=12 because the circle with radius 5 touches 12 lattice points: (+-1,+-2), (+-2,+-1), (+-5,0), (0,+-5); but no circle touches more, until the radius is sqrt(65). %Y A071339 Cf. A004018, A071339-A071347, A071383-A071385. %K A071339 easy,nonn %O A071339 0,2 %A A071339 _Hugo Pfoertner_, May 22 2002 %E A071339 Edited by _Don Reble_, Nov 06 2005