A342533 a(n) is the number of n-gons in A000940 that display symmetry (reflection / rotation).

1, 2, 4, 11, 24, 81, 193, 772, 1920, 8735, 23040

Offset: 3

Author

Ian Mooney, Mar 14 2021

Keywords

• nonn
• more

Examples

			Of the A000940(6)=12 hexagons, 11 have symmetry and 1 is asymmetric, so a(6)=11.
		

Crossrefs

Cf. A000940.

Formula

a(p) = (2^((p-1)/2)*((p-1)/2)!)/2 for prime p.