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 A274823 #11 Jul 10 2016 22:56:23 %S A274823 1,7,65 %N A274823 Total number of regions in all arrangements of n circles in the affine plane, excluding the regions that do not belong to the circles. %C A274823 In other words: not counting the regions between circles. %C A274823 Consider the arrangements of n circles described in A250001. %Y A274823 Row sums of triangle A274819. %Y A274823 For another version see A274822. %Y A274823 Cf. A250001, A274777. %K A274823 nonn,hard,bref,more %O A274823 1,2 %A A274823 _Omar E. Pol_, Jul 07 2016