OFFSET
1,3
COMMENTS
The order of a polyomino is defined as the minimum number of congruent copies required to tile a rectangle. The order is undefined if the polyomino cannot tile a rectangle. No example of a non-rectangular polyomino is known for which its order is odd.
From Zachary DeStefano, Feb 16 2026: (Start)
a(10) is known to be at least 138 (K. Dahlke). The main obstacle to determining the exact value of a(10) is deciding if the following polyomino can tile a rectangle.
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This is also the only remaining polyomino of height 2 with unknown order (K. Dahlke).
(End)
REFERENCES
S. W. Golomb, Polyominoes, second edition, Chapter 8, pp. 97-110, Princeton University Press, 1994.
LINKS
K. Dahlke, 10-omino, Order 138.
K. Dahlke, The Gun Theorem. [Cached copy at the Wayback Machine]
E. Friedman, Polyominoes in Rectangles
M. Garvie and J. Burkardt, A Parallelizable Integer Linear Programming Approach for Tiling Finite Regions of the Plane with Polyominoes, Algorithms, 15 (2022).
M. Reid, Rectifiable polyomino page. [Cached copy at the Wayback Machine]
R. Stanley, What are the most attractive Turing undecidable problems in mathematics?, MathOverflow.
H. Tulleken, Polyominoes 2.2: How they fit together (2019).
CROSSREFS
KEYWORD
nonn,hard,more
AUTHOR
William Rex Marshall, Dec 19 2006
EXTENSIONS
a(7)-a(9) confirmed by Zachary DeStefano, Feb 16 2026
STATUS
approved
