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A164644
Number of reduced words of length n in Coxeter group on 27 generators S_i with relations (S_i)^2 = (S_i S_j)^7 = I.
0
1, 27, 702, 18252, 474552, 12338352, 320797152, 8340725601, 216858856500, 5638330032075, 146596574673900, 3811510781360100, 99099276151168800, 2576581071661350000, 66991105048200214050, 1741768658063341610625
OFFSET
0,2
COMMENTS
The initial terms coincide with those of A170746, although the two sequences are eventually different.
Computed with MAGMA using commands similar to those used to compute A154638.
FORMULA
G.f.: (t^7 + 2*t^6 + 2*t^5 + 2*t^4 + 2*t^3 + 2*t^2 + 2*t + 1)/(325*t^7 - 25*t^6 - 25*t^5 - 25*t^4 - 25*t^3 - 25*t^2 - 25*t + 1).
CROSSREFS
Sequence in context: A163179 A163527 A164017 * A164969 A165445 A165979
KEYWORD
nonn
AUTHOR
John Cannon and N. J. A. Sloane, Dec 03 2009
STATUS
approved