A162804 Number of reduced words of length n in Coxeter group on 18 generators S_i with relations (S_i)^2 = (S_i S_j)^3 = I.

1, 18, 306, 5049, 83232, 1370880, 22579128, 371880576, 6124915584, 100877977152, 1661470525440, 27364587522048, 450697523867136, 7423033790767104, 122258117131149312, 2013603551504732160, 33164254102629777408

Offset: 0

Author

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

Keywords

• nonn

Comments

The initial terms coincide with those of A170737, 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 (16, 16, -136).

Formula

G.f.: (t^3 + 2*t^2 + 2*t + 1)/(136*t^3 - 16*t^2 - 16*t + 1)