A075222 Number of polyiamonds with n cells that tile the plane isohedrally but not by translation or by 180-degree rotation (Conway criterion).

0, 0, 0, 0, 0, 0, 2, 10, 22, 54, 52, 534, 523, 1339, 3218, 9315, 2177, 29426, 15423, 101314, 140072, 110794, 46748, 1639279, 710736, 970251, 3002062, 8462256, 895291, 29458807

Offset

1,7

Comments

A tiling is isohedral if the symmetries of the tiling act transitively on the tiles; a shape is anisohedral if it tiles the plane, but not isohedrally.

References

Branko Grünbaum and G. C. Shephard, Tilings and Patterns. W. H. Freeman, New York, 1987, Section 9.4.

Links

Table of n, a(n) for n=1..30.

Joseph Myers, Polyiamond tiling

Crossrefs

Cf. A071332, A075216, A075217, A075218, A075219, A075220, A075221, A075223, A075224, A075204, A075213.

Sequence in context: A218612 A218548 A079605 * A333703 A120548 A284360

Adjacent sequences: A075219 A075220 A075221 * A075223 A075224 A075225

Keyword

hard,nonn

Author

Joseph Myers, Sep 08 2002

Extensions

More terms from Joseph Myers, Nov 11 2003

a(29) and a(30) from Joseph Myers, Nov 21 2010

Status

approved