A211179 Number of free polypentagrams with n cells.

1, 1, 5, 31, 238, 2020, 17754, 160820, 1479536, 13792972, 129839465

Offset: 1

Author

George Sicherman, Feb 01 2013

Keywords

• nonn
• hard
• more

Comments

A polypentagram is a plane figure made of five-pointed stars joined edge to edge. Free means that mirror images are counted as the same polypentagram.

Examples

			Five different figures can be formed by joining 3 pentagrams, so a(3) = 5.
		

Links

• George Sicherman, Catalogue of Polypentagrams

Crossrefs

Cf. A103465, A000105, A000507.

Extensions

a(6)-a(11) from Aaron N. Siegel, May 23 2022