A075218 Number of polyiamonds with 2n cells that tile the plane both by translation and by 180-degree rotation (Conway criterion).

1, 2, 8, 24, 61, 269, 501, 2121, 4709, 14978, 26675, 123081, 179707, 660366, 1479114

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, A075217, A075219, A075220, A075221, A075222, A075223, A075224, A075200, A075209.

Extensions

More terms from Joseph Myers, Nov 11 2003

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