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 A288557 #14 Jul 09 2025 04:43:54 %S A288557 1,1,1,6,139 %N A288557 Number of connected one-sided arrangements of n circles in the affine plane, in the sense that the union of the boundaries of the circles is a connected set. %C A288557 These counts are not reduced for mirror symmetry. %C A288557 See A250001, the main entry for this problem, for further information. %Y A288557 Cf. A250001, A275923, A275924, A288554-A288568. %K A288557 nonn,more %O A288557 0,4 %A A288557 _N. J. A. Sloane_, Jun 13 2017, based on information supplied by _Jon Wild_ on Aug 31 2016