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A154639
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a(n) is the number of reduced words of length n (i.e., all possible length-reducing cancellations have been applied) in the generators of the "Apollonian reflection group" in three dimensions. This is a Coxeter group with five generators, satisfying the identities (S_i)^2 = (S_i S_j)^3 = I.
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0
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OFFSET
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0,2
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COMMENTS
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ABA and BAB are equal, but are counted as distinct reduced words.
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LINKS
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EXAMPLE
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All 80 squarefree words of length 3 are counted, so a(3) = 80.
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CROSSREFS
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For other sequences relating to the 3-dimensional case, see A154638-A154645.
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KEYWORD
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more,nonn
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AUTHOR
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STATUS
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approved
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