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OFFSET
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1,1
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COMMENTS
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Here the semigroup is under boolean matrix multiplication (not the same as GF(2) matrix multiplication). It is known that a(4) >= 24846, generated by the three matrices [[0,0,0,1],[1,0,0,0],[0,1,0,0],[0,0,1,0]] and [[0,0,0,1],[0,0,1,0],[0,1,0,0],[1,0,0,1]] and [[0,0,0,0],[0,0,0,1],[0,0,1,0],[0,1,0,0]].
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LINKS
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EXAMPLE
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For n = 1 the maximum size is 2, generated by the three matrices [0] and [1] and [1].
For n = 2 the maximum size is 16, generated by the three matrices [[0,1],[1,1]] and [[0,1],[1,0]] and [[0,0],[0,1]].
For n = 3 the maximum size is 440, generated by the three matrices [[0,0,1],[1,0,0],[0,1,0]] and [[0,0,1],[0,1,0],[1,0,1]] and [[0,0,0],[0,0,1],[0,1,0]].
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CROSSREFS
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KEYWORD
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nonn,hard,more,bref
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AUTHOR
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STATUS
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approved
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