

A217720


Number of onesided polydrafters with n cells.


2




OFFSET

1,1


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. Onesided means that distinct mirror images are counted separately.
For odd n, an ndrafter cannot have mirror symmetry, so odd entries in this sequence are double those in A056842.


REFERENCES

Ed Pegg, Jr., Polyform puzzles, in Tribute to a Mathemagician, Peters, 2005, pp. 119125.


LINKS

Table of n, a(n) for n=1..7.
K. Ishino, Polydrafters
Bernd Karl Rennhak, Drafter


EXAMPLE

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


CROSSREFS

Cf. A056842 (number of twosided polydrafters).
Sequence in context: A151299 A150717 A150718 * A151300 A150719 A150720
Adjacent sequences: A217717 A217718 A217719 * A217721 A217722 A217723


KEYWORD

nonn,more


AUTHOR

George Sicherman, Mar 21 2013


STATUS

approved



