A307455 a(n) is the number of canonical polygons with n edges having exactly 1 line of reflection symmetry.

1, 0, 2, 2, 1, 7, 6, 28, 27, 107, 94, 488, 386, 2066, 1630, 8392, 6780, 34962, 28056, 147356, 117621, 622558, 500525, 2657666, 2149374

Offset: 3

Author

Lars Blomberg, Apr 09 2019

Keywords

• nonn
• more

Comments

For n even, the symmetry line passes through two opposite vertices, or cuts through two opposite edges. For n odd it passes through one vertex and cuts the opposite edge. That explains the even-odd irregularity in the sequence.

Links

• Lars Blomberg, Examples of canonical polygons with exactly 1 line of reflection symmetry

Crossrefs

Cf. A052436, A307387, A307391, A307426, A307454, A307455, A307456, A307519.