A217720 Number of one-sided polydrafters with n cells.

2, 8, 28, 116, 474, 2001, 8508, 37162, 163730, 729683, 3269602, 14773831

Offset: 1

Author

George Sicherman, Mar 21 2013

Keywords

• nonn
• more

Comments

A polydrafter is a plane figure formed by joining equal triangles with angles of 30, 60, and 90 degrees with certain restrictions on how they are joined. See A056842 for details. One-sided means that distinct mirror images are counted separately.

For odd n, an n-drafter cannot have mirror symmetry, so odd entries in this sequence are double those in A056842.

Examples

			There are 6 two-sided didrafters, two have distinct mirror images, so there are 8 one-sided didrafters. Thus a(2) = 8.
		

References

• Ed Pegg, Jr., Polyform puzzles, in Tribute to a Mathemagician, Peters, 2005, pp. 119-125.

Links

• K. Ishino, Polydrafters
• Bernd Karl Rennhak, Drafter

Crossrefs

Cf. A056842 (number of two-sided polydrafters).

Extensions

a(8)-a(12) from Aaron N. Siegel, May 13 2022