cp's OEIS Frontend

A358783 The number of edges formed when every pair of n points, placed at the vertices of a regular n-gon, are connected by a circle and where the points lie at the ends of the circle's diameter.

%I A358783 #19 Mar 25 2024 17:45:03
%S A358783 2,12,16,120,138,532,432,1548,1450,3696,3120,7488,6874,13560,12000,
%T A358783 23256,20970,36328,32400,54852,51194,79672,70752,113100,105274,154764,
%U A358783 144480,206712,195810,272800,255808,352176,335002,446740,422784,560920,534698,695760,659440,850340,815682
%N A358783 The number of edges formed when every pair of n points, placed at the vertices of a regular n-gon, are connected by a circle and where the points lie at the ends of the circle's diameter.
%C A358783 Conjecture: for odd values of n all vertices are simple, other than those defining the diameters of the circles. No formula for n, or only the odd values of n, is currently known.
%C A358783 See A358746 and A358782 for images of the circles.
%C A358783 The author thanks Zach Shannon some of whose code was used in the generation of this sequence.
%C A358783 If n is odd, the circle containing the initial n points is not part of the graph (compare A370976-A370979). - _N. J. A. Sloane_, Mar 25 2024
%F A358783 a(n) = A358746(n) + A358782(n) - 1 by Euler's formula.
%Y A358783 Cf. A358746 (vertices), A358782 (regions), A359009 (k-gons), A135565, A344899.
%Y A358783 See allso A370976-A370979.
%K A358783 nonn
%O A358783 2,1
%A A358783 _Scott R. Shannon_, Nov 30 2022