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 A288567 #11 Jul 09 2025 04:44:40 %S A288567 1,1,1,3,21,980 %N A288567 Number of connected arrangements of n circles in the affine plane, in the sense that the union of the boundaries of the circles is a connected set and every circle intersects all the other circles. %C A288567 These counts have been reduced for mirror symmetry. %C A288567 See A250001, the main entry for this problem, for further information. %Y A288567 Cf. A250001, A275923, A275924, A288554-A288568. %K A288567 nonn,more %O A288567 0,4 %A A288567 _N. J. A. Sloane_, Jun 13 2017, based on information supplied by _Jon Wild_