A372616 - OEIS

A372616

Number of curved edges among all distinct circles that can be constructed from the 3 vertices and the equally spaced 3*n points placed on the sides of an equilateral triangle, using only a compass.

%I #10 May 10 2024 08:49:31

%S 12,207,1104,4359,14880,32523,73662,121605,223290,329286,554286,

%T 722841,1145091

%N Number of curved edges among all distinct circles that can be constructed from the 3 vertices and the equally spaced 3*n points placed on the sides of an equilateral triangle, using only a compass.

%C A circle is constructed for every pair of the 3 + 3*n points, the first point defines the circle's center while the second the radius distance.

%C See A372614 and A372615 for images of the circles.

%F a(n) = A372614(n) + A372615(n) - 1 by Euler's formula.

%Y Cf. A372614 (vertices), A372615 (regions), A372617 (k-gons), A372682 (number of circles), A371375, A356358, A360353.

%K nonn,more

%O 0,1

%A _Scott R. Shannon_, May 07 2024