A075220 Number of polyiamonds with n cells that tile the plane by 180-degree rotation (Conway criterion).

1, 1, 1, 3, 4, 12, 21, 56, 111, 261, 462, 1431, 1875, 4696, 9410, 20099, 24034, 77884, 79925, 266786, 358096, 658594, 796571, 3227163, 2980476, 6268017, 10167660, 24321735, 21477012, 85964698

Offset: 1

Author

Joseph Myers, Sep 08 2002

Keywords

• hard
• nonn

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, A075221, A075222, A075223, A075224, A075202, A075211.

Extensions

More terms from Joseph Myers, Nov 11 2003

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