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 A288562 #17 Jul 09 2025 04:44:20 %S A288562 1,1,1,4,45,5108,4598809 %N A288562 Number of arrangements of n pseudo-circles in the affine plane with the property that every pseudo-circle intersects all the other circles. %C A288562 Arrangements in A288559 that are connected, with the property that every pseudo-circle intersects all the other pseudo-circles. %C A288562 These counts have been reduced for mirror symmetry. %C A288562 See A250001, the main entry for this problem, for further information. %Y A288562 Cf. A250001, A275923, A275924, A288554-A288568. %K A288562 nonn,more %O A288562 0,4 %A A288562 _N. J. A. Sloane_, Jun 12 2017, based on information supplied by _Jon Wild_ on Aug 31 2016 %E A288562 a(6) from _Manfred Scheucher_, May 09 2018