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A164970
Number of reduced words of length n in Coxeter group on 28 generators S_i with relations (S_i)^2 = (S_i S_j)^8 = I.
0
1, 28, 756, 20412, 551124, 14880348, 401769396, 10847773692, 292889889306, 7908027001056, 213516728753328, 5764951668909888, 155653694859957840, 4202649755802415008, 113471543260421145072, 3063731664082781293056
OFFSET
0,2
COMMENTS
The initial terms coincide with those of A170747, although the two sequences are eventually different.
Computed with MAGMA using commands similar to those used to compute A154638.
FORMULA
G.f. (t^8 + 2*t^7 + 2*t^6 + 2*t^5 + 2*t^4 + 2*t^3 + 2*t^2 + 2*t + 1)/(351*t^8 -
26*t^7 - 26*t^6 - 26*t^5 - 26*t^4 - 26*t^3 - 26*t^2 - 26*t + 1)
CROSSREFS
Sequence in context: A163548 A164025 A164664 * A165456 A165980 A166422
KEYWORD
nonn
AUTHOR
John Cannon and N. J. A. Sloane, Dec 03 2009
STATUS
approved