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.

12, 207, 1104, 4359, 14880, 32523, 73662, 121605, 223290, 329286, 554286, 722841, 1145091

Offset: 0

Author

Scott R. Shannon, May 07 2024

Keywords

• nonn
• more

Comments

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.

See A372614 and A372615 for images of the circles.

Crossrefs

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

Formula

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