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A166690
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Number of reduced words of length n in Coxeter group on 38 generators S_i with relations (S_i)^2 = (S_i S_j)^12 = I.
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0
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1, 38, 1406, 52022, 1924814, 71218118, 2635070366, 97497603542, 3607411331054, 133474219248998, 4938546112212926, 182726206151878262, 6760869627619494991, 250152176221921288656, 9255630520211086718568
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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 A170757, 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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Table of n, a(n) for n=0..14.
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FORMULA
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G.f. (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)/(666*t^12 - 36*t^11 - 36*t^10 - 36*t^9 - 36*t^8
- 36*t^7 - 36*t^6 - 36*t^5 - 36*t^4 - 36*t^3 - 36*t^2 - 36*t + 1)
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CROSSREFS
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Sequence in context: A165687 A166170 A166432 * A167091 A167492 A167827
Adjacent sequences: A166687 A166688 A166689 * A166691 A166692 A166693
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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, Dec 03 2009
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STATUS
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approved
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