A307455 - OEIS

%I #11 Apr 22 2019 11:46:40

%S 1,0,2,2,1,7,6,28,27,107,94,488,386,2066,1630,8392,6780,34962,28056,

%T 147356,117621,622558,500525,2657666,2149374

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

%C 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.

%H Lars Blomberg, <a href="/A307455/a307455.pdf">Examples of canonical polygons with exactly 1 line of reflection symmetry</a>

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

%K nonn,more

%O 3,3

%A _Lars Blomberg_, Apr 09 2019