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A162807
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Number of reduced words of length n in Coxeter group on 21 generators S_i with relations (S_i)^2 = (S_i S_j)^3 = I.
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0
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1, 21, 420, 8190, 159600, 3108210, 60532290, 1178845500, 22957618110, 447091673490, 8706955895400, 169564956368010, 3302218915041690, 64309571936658300, 1252406684472377910, 24390187277913766890
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OFFSET
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0,2
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COMMENTS
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The initial terms coincide with those of A170740, although the two sequences are eventually different.
Computed with MAGMA using commands similar to those used to compute A154638.
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LINKS
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FORMULA
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G.f.: (t^3 + 2*t^2 + 2*t + 1)/(190*t^3 - 19*t^2 - 19*t + 1).
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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