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A163092
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Number of reduced words of length n in Coxeter group on 16 generators S_i with relations (S_i)^2 = (S_i S_j)^4 = I.
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0
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1, 16, 240, 3600, 53880, 806400, 12069120, 180633600, 2703470280, 40461750000, 605574696720, 9063392310000, 135648138214680, 2030190989349600, 30385049935084320, 454760790684530400, 6806221388012959080, 101865971146974325200, 1524586916316221551920
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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 A170735, 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)/(105*t^4 - 14*t^3 - 14*t^2 - 14*t + 1).
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MATHEMATICA
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CoefficientList[ Series[(t^4 + 2*t^3 + 2*t^2 + 2*t + 1)/(105*t^4 - 14*t^3 - 14*t^2 - 14*t + 1), {t, 0, 16}], t] (* Jean-François Alcover, Nov 26 2013 *)
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PROG
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(PARI) Vec((t^4 + 2*t^3 + 2*t^2 + 2*t + 1)/(105*t^4 - 14*t^3 - 14*t^2 - 14*t + 1) + O(t^20)) \\ 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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EXTENSIONS
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STATUS
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approved
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