A370979 Draw a regular n-gon and the enclosing circle, then for each pair of vertices X, Y, draw a circle with diameter XY; the union of these figures is the graph H_n; sequence gives number of edges in H_n.

1, 4, 21, 20, 135, 144, 553, 440, 1575, 1460, 3729, 3132, 7527, 6888, 13605, 12016, 23307, 20988, 36385, 32420, 54915, 51216, 79741, 70776, 113175, 105300, 154845, 144508, 206799, 195840, 272893, 255840, 352275, 335036, 446845, 422820, 561031, 534736, 695877, 659480, 850463, 815724

Offset: 1

Author

Scott R. Shannon and N. J. A. Sloane, Mar 25 2024

Keywords

• nonn

Comments

For the numbers of vertices and regions in G_n see A358746 and A370978.

H_n is the union of the graph G_n defined in A370976 and the polygon through the initial n points.

Crossrefs

Cf. A358746, A358782, A358783, A370976, A370977, A370978.

Formula

a(n) = A358783(n) if n even, a(n) = A358783(n) + n if n odd.

a(n) = A358783(n) + n if n even, a(n) = A358783(n) + 3*n if n odd.