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A213950
Number of free poly-IH9-tiles (holes allowed) with n cells.
0
1, 2, 7, 24, 99, 416, 1852, 8386, 38798, 181531, 858570, 4092042, 19636172, 94750922
OFFSET
1,2
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: A150435 A150436 A197553 * A123764 A150437 A150438
KEYWORD
hard,nonn,more
AUTHOR
Joseph Myers, Jun 26 2012
STATUS
approved