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A163091
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Number of reduced words of length n in Coxeter group on 15 generators S_i with relations (S_i)^2 = (S_i S_j)^4 = I.
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0
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1, 15, 210, 2940, 41055, 573300, 8005725, 111793500, 1561106820, 21799608285, 304414090890, 4250899269435, 59360407871310, 828920611657320, 11575213262103855, 161638593827703720, 2257153663002754425, 31519345335542489880, 440142444293996873520, 6146237150764726493205
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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 A170734, 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)/(91*t^4 - 13*t^3 - 13*t^2 - 13*t + 1).
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MATHEMATICA
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CoefficientList[Series[(t^4 + 2 t^3 + 2 t^2 + 2 t + 1)/(91 t^4 - 13 t^3 - 13 t^2 - 13 t + 1), {t, 0, 20}], t] (* Jinyuan Wang, Mar 22 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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EXTENSIONS
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STATUS
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approved
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