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A164781
Number of reduced words of length n in Coxeter group on 12 generators S_i with relations (S_i)^2 = (S_i S_j)^8 = I.
0
1, 12, 132, 1452, 15972, 175692, 1932612, 21258732, 233845986, 2572305120, 28295348400, 311248745280, 3423735239760, 37661077095840, 414271732097520, 4556987777548800, 50126851522277970, 551395212406754100
OFFSET
0,2
COMMENTS
The initial terms coincide with those of A003954, 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)/(55*t^8 - 10*t^7 - 10*t^6 - 10*t^5 - 10*t^4 - 10*t^3 - 10*t^2 - 10*t + 1).
MATHEMATICA
coxG[{8, 55, -10}] (* The coxG program is at A169452 *) (* Harvey P. Dale, Oct 17 2015 *)
CROSSREFS
Sequence in context: A163957 A063813 A164601 * A165266 A165807 A166372
KEYWORD
nonn
AUTHOR
John Cannon and N. J. A. Sloane, Dec 03 2009
STATUS
approved