The OEIS is supported by the many generous donors to the OEIS Foundation.

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.

5

`%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
`