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A163149
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Number of reduced words of length n in Coxeter group on 22 generators S_i with relations (S_i)^2 = (S_i S_j)^4 = I.
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0
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1, 22, 462, 9702, 203511, 4268880, 89544840, 1878307200, 39399681090, 826454197800, 17335839305400, 363639419173800, 7627760320511100, 160001156198268000, 3356210592504924000, 70400425902447564000
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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 A170741, 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^4 + 2*t^3 + 2*t^2 + 2*t + 1)/(210*t^4 - 20*t^3 - 20*t^2 - 20*t + 1).
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MATHEMATICA
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CoefficientList[Series[(t^4 + 2 t^3 + 2 t^2 + 2 t + 1)/(210 t^4 - 20 t^3 - 20 t^2 - 20 t + 1), {t, 0, 16}], t] (* Jinyuan Wang, Mar 23 2020 *)
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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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