A075217 Number of polyiamonds with 2n cells that tile the plane by translation but not by 180-degree rotation (Conway criterion).

0, 0, 0, 0, 1, 22, 38, 504, 1468, 6945, 11046, 115186, 119496, 677774, 2013619

Offset: 1

Author

Joseph Myers, Sep 08 2002

Keywords

• hard
• nonn

Comments

Polyiamonds with an odd number of cells have different numbers of triangles with the two orientations and so cannot tile by translation.

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, A075218, A075219, A075220, A075221, A075222, A075223, A075224, A075199, A075208.

Extensions

More terms from Joseph Myers, Nov 11 2003

a(15) (30-iamonds) from Joseph Myers, Nov 21 2010