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Search: id:A166877
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| A166877 |
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Number of reduced words of length n in Coxeter group on 6 generators S_i with relations (S_i)^2 = (S_i S_j)^13 = I. |
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+0
1
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| 1, 6, 30, 150, 750, 3750, 18750, 93750, 468750, 2343750, 11718750, 58593750, 292968750, 1464843735, 7324218600, 36621092640, 183105461400, 915527298000, 4577636445000, 22888182000000, 114440908875000, 572204538750000
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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The initial terms coincide with those of A003948, although the two sequences are eventually different.
Computed with MAGMA using commands similar to those used to compute A154638.
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FORMULA
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G,f.: (t^13 + 2*t^12 + 2*t^11 + 2*t^10 + 2*t^9 + 2*t^8 + 2*t^7 + 2*t^6 + 2*t^5 +
2*t^4 + 2*t^3 + 2*t^2 + 2*t + 1)/(10*t^13 - 4*t^12 - 4*t^11 - 4*t^10 -
4*t^9 - 4*t^8 - 4*t^7 - 4*t^6 - 4*t^5 - 4*t^4 - 4*t^3 - 4*t^2 - 4*t + 1)
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CROSSREFS
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Sequence in context: A165777 A166364 A166500 this_sequence A167107 A167651 A167897
Adjacent sequences: A166874 A166875 A166876 this_sequence A166878 A166879 A166880
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KEYWORD
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nonn
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AUTHOR
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John Cannon (john(AT)maths.usyd.edu.au) and N. J. A. Sloane (njas(AT)research.att.com), Dec 03 2009
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