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 A288556 #13 Jul 09 2025 04:43:48 %S A288556 1,1,2,11,183 %N A288556 Number of connected one-sided arrangements of n circles in the affine plane, in the sense that the union of the solid circles is a connected set. %C A288556 These counts are not reduced for mirror symmetry. %C A288556 See A250001, the main entry for this problem, for further information. %Y A288556 Cf. A250001, A275923, A275924, A288554-A288568. %K A288556 nonn,more %O A288556 0,3 %A A288556 _N. J. A. Sloane_, Jun 13 2017, based on information supplied by _Jon Wild_