A197551 Number of free poly-IH18-tiles (holes allowed) with n cells.

1, 1, 4, 10, 37, 147, 637, 2823, 13020, 60649, 286549, 1364667, 6547108, 31586568

Offset: 1

Author

Joseph Myers, Oct 16 2011

Keywords

• hard
• nonn

Comments

Equivalently, polyhexes where two polyhexes are considered equivalent if and only if they are related by a translation, a rotation of order 3 or a reflection or glide reflection in a line perpendicular to the sides of the hexagons.

References

• Branko Grünbaum and G. C. Shephard, Tilings and Patterns. W. H. Freeman, New York, 1987, Sections 6.2 and 9.4.

Crossrefs

Cf. A000228, A001207, A006535, A057973, A197549, A197550, A197552, A197553, A197554.