[seqfan] A250001

[Benoît Jubin]

Dear seqfans,

Following the article in QuantaMagazine which raises awareness of A250001,
I submitted a sequence (table) which counts the configurations with given
numbers of intersections. It is A261070.

I hope T(4,1) is correct, and I think T(n,1) is not to hard to compute from
T(0,0), T(1,0), ..., T(n-2,0) in a similar way: first draw the two
intersecting circles; they divide the plane in 4 regions (2 of which play
similar roles); then put the n-2 other circles in some of these regions (or
put n-2-k "concentrically surrounding" the whole figure and then k circles
in the remaining regions).

Benoît