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.

1, 19, 342, 5985, 104652, 1828503, 31947930, 558187605, 9752543136, 170394389307, 2977095147966, 52015183033833, 908798387526612, 15878335141888767, 277422946995884994, 4847075643050582301

Offset: 0

Author

John Cannon and N. J. A. Sloane, Dec 03 2009

Keywords

• nonn

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.

Links

• Index entries for linear recurrences with constant coefficients, signature (17, 17, -153).

Programs

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 *)

Formula

G.f.: (t^3 + 2*t^2 + 2*t + 1)/(153*t^3 - 17*t^2 - 17*t + 1)