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

Author

Joseph Myers, Sep 08 2002

Keywords

• hard
• nonn

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

• Joseph Myers, Polyiamond tiling

Crossrefs

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

Extensions

More terms from Joseph Myers, Nov 11 2003

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