3818273456

Appears in sequences

• Number of ways to color vertices of a 9-gon using <= n colors, allowing rotations and reflections.at n=16A060561
• For n >= 3, draw a regular n-sided polygon and its n*(n-3)/2 diagonals, so there are n*(n-1)/2 lines; a(n) is the number of ways to choose a subset of these lines (subsets differing by a rotation or reflection are regarded as identical). a(1)=1, a(2)=2 by convention.at n=8A191563