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A162805
Number of reduced words of length n in Coxeter group on 19 generators S_i with relations (S_i)^2 = (S_i S_j)^3 = I.
0
1, 19, 342, 5985, 104652, 1828503, 31947930, 558187605, 9752543136, 170394389307, 2977095147966, 52015183033833, 908798387526612, 15878335141888767, 277422946995884994, 4847075643050582301
OFFSET
0,2
COMMENTS
The initial terms coincide with those of A170738, although the two sequences are eventually different.
Computed with MAGMA using commands similar to those used to compute A154638.
FORMULA
G.f.: (t^3 + 2*t^2 + 2*t + 1)/(153*t^3 - 17*t^2 - 17*t + 1)
MATHEMATICA
CoefficientList[Series[(t^3+2*t^2+2*t+1)/(153*t^3-17*t^2-17*t+1), {t, 0, 30}], t] (* Harvey P. Dale, Aug 14 2011 *)
CROSSREFS
Sequence in context: A202043 A142549 A049629 * A049664 A163110 A163453
KEYWORD
nonn
AUTHOR
John Cannon and N. J. A. Sloane, Dec 03 2009
STATUS
approved