A162809 Number of reduced words of length n in Coxeter group on 23 generators S_i with relations (S_i)^2 = (S_i S_j)^3 = I.

1, 23, 506, 10879, 233772, 5020785, 107832648, 2315920761, 49739020254, 1068244419627, 22942674541710, 492739584509403, 10582562979139536, 227281596017492709, 4881324494907605052, 104836155861245820165

Offset: 0

Author

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

Keywords

• nonn

Comments

The initial terms coincide with those of A170742, 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 (21, 21, -231).

Formula

G.f.: (t^3 + 2*t^2 + 2*t + 1)/(231*t^3 - 21*t^2 - 21*t + 1)