A162812 Number of reduced words of length n in Coxeter group on 26 generators S_i with relations (S_i)^2 = (S_i S_j)^3 = I.

1, 26, 650, 15925, 390000, 9547200, 233715300, 5721300000, 140056207200, 3428545582800, 83930052960000, 2054589502867200, 50295905665012800, 1231232868141120000, 30140313720487027200, 737828346427571692800

Offset

0,2

Comments

The initial terms coincide with those of A170745, 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..15.

Index entries for linear recurrences with constant coefficients, signature (24, 24, -300).

Formula

G.f.: (t^3 + 2*t^2 + 2*t + 1)/(300*t^3 - 24*t^2 - 24*t + 1)

Crossrefs

Sequence in context: A014913 A285397 A106793 * A163177 A163526 A163995

Adjacent sequences: A162809 A162810 A162811 * A162813 A162814 A162815

Keyword

nonn

Author

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

Status

approved