A340687 The number of edges on a concave circular triangle formed by the straight line segments mutually connecting all vertices and all points that divide the sides into n equal parts.

3, 21, 51, 177, 354, 852, 1686, 3036, 5994, 8550, 12933, 16938, 24303, 30192, 41616, 52581, 66600, 82857, 101199, 128409, 153669, 194505, 227193, 271635, 320898, 368703, 431640, 490884, 578805, 646869, 744717, 851214, 943068, 1071741, 1195638, 1367913, 1523694, 1713300, 1885389, 2082696

Offset

1,1

Comments

The terms are from numeric computation - no formula for a(n) is currently known.

See A340685 for images of the regions and A340686 for images of the vertices.

Links

Table of n, a(n) for n=1..40.

Wikipedia, Circular triangle.

Crossrefs

Cf. A340685 (regions), A340686 (vertices), A340688 (n-gons), A340613, A007678, A092867.

Sequence in context: A219069 A027499 A303834 * A152773 A039595 A033567

Adjacent sequences: A340684 A340685 A340686 * A340688 A340689 A340690

Keyword

nonn

Author

Scott R. Shannon and N. J. A. Sloane, Jan 16 2021

Status

approved