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A162744
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Number of reduced words of length n in Coxeter group on 7 generators S_i with relations (S_i)^2 = (S_i S_j)^3 = I.
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0
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1, 7, 42, 231, 1260, 6825, 36960, 200025, 1082550, 5858475, 31704750, 171577875, 928536000, 5024998125, 27194002500, 147166963125, 796429856250, 4310074059375, 23325015131250, 126228998109375, 683118955312500
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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 A003949, 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)/(15*t^3 - 5*t^2 - 5*t + 1)
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MATHEMATICA
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coxG[{3, 15, -5}] (* The coxG program is at A169452 *) (* or *) LinearRecurrence[{5, 5, -15}, {1, 7, 42, 231}, 30] (* Harvey P. Dale, Oct 02 2021 *)
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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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