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A125709
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Number of n-indecomposable polyominoes with at least n cells.
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6
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OFFSET
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1,2
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COMMENTS
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A polyomino is called n-indecomposable if it cannot be partitioned (along cell boundaries) into two or more polyominoes each with at least n cells.
MacKinnon incorrectly gives a(3) = 42.
For full lists of drawings of these polyominoes for n <= 6, see the links in A125759.
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LINKS
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EXAMPLE
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The five 2-indecomposable polyominoes:
...................X.
XX..XXX..XX..XXX..XXX
..........X...X....X.
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CROSSREFS
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KEYWORD
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nonn,more
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AUTHOR
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EXTENSIONS
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a(4) and a(5) from Peter Pleasants, Feb 13 2007
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STATUS
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approved
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