A162791 Number of reduced words of length n in Coxeter group on 16 generators S_i with relations (S_i)^2 = (S_i S_j)^3 = I.

1, 16, 240, 3480, 50400, 729120, 10547880, 152586000, 2207316720, 31931110680, 461916453600, 6682097644320, 96663430749480, 1398336169885200, 20228374156231920, 292624284336944280, 4233111921066520800

Offset: 0

Author

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

Keywords

• nonn

Comments

The initial terms coincide with those of A170735, 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 (14, 14, -105).

Programs

Mathematica

CoefficientList[Series[(t^3+2t^2+2t+1)/(105t^3-14t^2-14t+1), {t,0,30}],t] (* Harvey P. Dale, Oct 02 2011 *)

Formula

G.f.: (t^3 + 2*t^2 + 2*t + 1)/(105*t^3 - 14*t^2 - 14*t + 1)