A335192 a(n) is the number of regions inside an n-gon formed by the straight line segments connecting vertex k to vertex 3k mod n.

1, 2, 4, 7, 8, 6, 12, 19, 23, 18, 31, 39, 37, 28, 56, 57, 68, 60, 76, 93, 103, 72, 119, 133, 129, 126, 164, 163, 184, 146, 196, 223, 239, 206, 263, 283, 277, 240, 328, 317, 356, 336, 372, 409, 431, 348, 463, 489, 481, 474, 548, 543, 584, 510, 604, 651, 679

Offset: 3

Author

Lars Blomberg, May 26 2020

Keywords

• nonn

Comments

The envelope of the lines form a nephroid.

Links

• Lars Blomberg, Table of n, a(n) for n = 3..300
• Lars Blomberg, Illustration for n = 10
• Lars Blomberg, Illustration for n = 20
• Lars Blomberg, Illustration for n = 40
• Lars Blomberg, Illustration for n = 200

Crossrefs

Cf. A335193 (edges), A335194 (vertices), A335195 (n-gons).