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A350874
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a(n) is the number of nonisomorphic magmas with n elements which satisfy the identity (xx)y = x(xy) for all x and y (so-called left-alternative magmas).
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2
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OFFSET
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0,3
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COMMENTS
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Equivalently (by symmetry), a(n) also equals the number of nonisomorphic right-alternative magmas with n elements (that is, magmas satisfying the identity x(yy) = (xy)y for all x and y).
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LINKS
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EXAMPLE
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There are 10 non-isomorphic magmas with 2 elements, and 5 of these are left-alternative, so a(2) = 5.
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CROSSREFS
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KEYWORD
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nonn,more,hard
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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