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

3,3

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

Table of n, a(n) for n=3..27.

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

Crossrefs

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

Sequence in context: A021455 A271460 A248924 * A136502 A144502 A246945

Adjacent sequences: A307452 A307453 A307454 * A307456 A307457 A307458

Keyword

nonn,more

Author

Lars Blomberg, Apr 09 2019

Status

approved