A162743 Number of reduced words of length n in Coxeter group on 6 generators S_i with relations (S_i)^2 = (S_i S_j)^3 = I.

1, 6, 30, 135, 600, 2640, 11610, 51000, 224040, 984060, 4322400, 18985440, 83390760, 366280800, 1608831840, 7066542960, 31038691200, 136332618240, 598819808160, 2630222793600, 11552844224640, 50744069991360

Offset

0,2

Comments

The initial terms coincide with those of A003948, although the two sequences are eventually different.

Computed with MAGMA using commands similar to those used to compute A154638.

Links

Table of n, a(n) for n=0..21.

Index entries for linear recurrences with constant coefficients, signature (4, 4, -10).

Formula

G.f.: (t^3 + 2*t^2 + 2*t + 1)/(10*t^3 - 4*t^2 - 4*t + 1)

Crossrefs

Sequence in context: A247386 A317755 A036068 * A224290 A081895 A030280

Adjacent sequences: A162740 A162741 A162742 * A162744 A162745 A162746

Keyword

nonn

Author

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

Status

approved