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 A288560 #18 Jul 09 2025 04:44:07 %S A288560 1,1,2,11,156,16782 %N A288560 Number of connected arrangements of n pseudo-circles in the affine plane, in the sense that the union of the solid pseudo-circles is a connected set. %C A288560 Arrangements in A288559 that are connected (in the sense that the union of the solid pseudo-circles is a connected set). %C A288560 These counts have been reduced for mirror symmetry. %C A288560 See A250001, the main entry for this problem, for further information. %Y A288560 Cf. A250001, A275923, A275924, A288554-A288568. %K A288560 nonn,more %O A288560 0,3 %A A288560 _N. J. A. Sloane_, Jun 13 2017, based on information supplied by _Jon Wild_ on Aug 31 2016