A335129 a(n) is the number of distinct lines created inside an n-gon when connecting vertex k to vertex 2k mod n.

0, 1, 2, 2, 4, 5, 5, 7, 8, 8, 10, 11, 11, 13, 14, 14, 16, 17, 17, 19, 20, 20, 22, 23, 23, 25, 26, 26, 28, 29, 29, 31, 32, 32, 34, 35, 35, 37, 38, 38, 40, 41, 41, 43, 44, 44, 46, 47, 47, 49, 50, 50, 52, 53, 53, 55, 56, 56, 58, 59, 59, 61, 62, 62, 64, 65, 65

Offset: 3

Author

Lars Blomberg, May 24 2020

Keywords

• nonn

Comments

See A335057 for illustrations.

Crossrefs

Cf. A079978.

Cf. A335057 (regions), A335058 (edges), A335059 (vertices).

Formula

a(n) = n - 3 - A079978(n).

a(3) = 0, a(n) = n - 4 + sign(n mod 3) for n>=4. - Wesley Ivan Hurt, Dec 29 2021