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 A258186 #15 Jul 08 2015 23:21:42 %S A258186 0,0,0,0,0,0,0,0,0,0,0,0,1,1,2,2,3,3,6,6,7,7,10,10,13 %N A258186 a(n) is the maximal number of circles that can be enclosed by a closed chain of n circles; all circles' centers lie at coordinate points of the planar net 6.6.6. %C A258186 Inspired by A257594, in which the centers of circles can be considered to be placed on coordinate points of the planar net 3.3.3.3.3.3. See illustrations in the links. %H A258186 Kival Ngaokrajang, <a href="/A258186/a258186_1.pdf">Illustration for n = 0..11</a>, <a href="/A258186/a258186_2.pdf">for n = 12..22</a> %Y A258186 Cf. A257594. %K A258186 nonn,more %O A258186 0,15 %A A258186 _Kival Ngaokrajang_, May 23 2015