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

1,6

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

Table of n, a(n) for n=1..15.

Joseph Myers, Polyiamond tiling

Crossrefs

Cf. A071332, A075216, A075218, A075219, A075220, A075221, A075222, A075223, A075224, A075199, A075208.

Sequence in context: A043196 A043976 A131196 * A188156 A026061 A138040

Adjacent sequences: A075214 A075215 A075216 * A075218 A075219 A075220

Keyword

hard,nonn

Author

Joseph Myers, Sep 08 2002

Extensions

More terms from Joseph Myers, Nov 11 2003

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

Status

approved