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A163290
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Number of reduced words of length n in Coxeter group on 50 generators S_i with relations (S_i)^2 = (S_i S_j)^4 = I.
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0
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1, 50, 2450, 120050, 5881225, 288120000, 14114940000, 691488000000, 33875854559400, 1659571130851200, 81302047554268800, 3982970548016611200, 195124905996721243200, 9559128916780140902400, 468299754871670360217600
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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 A170769, 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)/(1176*t^4 - 48*t^3 - 48*t^2 - 48*t + 1).
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MATHEMATICA
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CoefficientList[Series[(t^4 + 2*t^3 + 2*t^2 + 2*t + 1)/(1176*t^4 - 48*t^3 - 48*t^2 - 48*t + 1), {t, 0, 50}], t] (* or *) Join[{1}, LinearRecurrence[ {48, 48, 48, -1176}, {50, 2450, 120050, 5881225}, 25]] (* G. C. Greubel, Dec 17 2016 *)
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PROG
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(PARI) Vec((t^4 + 2*t^3 + 2*t^2 + 2*t + 1)/(1176*t^4 - 48*t^3 - 48*t^2 - 48*t + 1) + O(t^50)) \\ G. C. Greubel, Dec 17 2016
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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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