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A197958
Number of free poly-IH4-tiles (holes allowed) with n cells.
2
1, 5, 11, 52, 186, 848, 3652, 16843, 77359, 363387, 1716033, 8185607, 39267086, 189509099
OFFSET
1,2
COMMENTS
Equivalently, one-sided poly-IH13-tiles or one-sided poly-IH15-tiles. IH4 is the generic isohedral tiling by 180-degree rotation (Conway criterion).
REFERENCES
Branko Grünbaum and G. C. Shephard, Tilings and Patterns. W. H. Freeman, New York, 1987, Sections 6.2 and 9.4.
CROSSREFS
Sequence in context: A149526 A249075 A089004 * A094107 A107009 A228865
KEYWORD
hard,nonn
AUTHOR
Joseph Myers, Oct 19 2011
STATUS
approved