A162808 Number of reduced words of length n in Coxeter group on 22 generators S_i with relations (S_i)^2 = (S_i S_j)^3 = I.

1, 22, 462, 9471, 194040, 3973200, 81355890, 1665833400, 34109413800, 698420207100, 14300767404000, 292820775324000, 5995762611069000, 122768506573020000, 2513793020863740000, 51472120400410710000

Offset: 0

Author

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

Keywords

• nonn

Comments

The initial terms coincide with those of A170741, 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 (20, 20, -210).

Programs

Mathematica

coxG[{3,210,-20}] (* The coxG program is at A169452 *) (* Harvey P. Dale, Mar 09 2018 *)

Formula

G.f.: (t^3 + 2*t^2 + 2*t + 1)/(210*t^3 - 20*t^2 - 20*t + 1)