A162827 Number of reduced words of length n in Coxeter group on 27 generators S_i with relations (S_i)^2 = (S_i S_j)^3 = I.

1, 27, 702, 17901, 456300, 11626875, 296261550, 7548913125, 192350632500, 4901203636875, 124885459968750, 3182152634578125, 81083061181687500, 2066042570916796875, 52643941196224218750, 1341397599294476953125

Offset

0,2

Comments

The initial terms coincide with those of A170746, 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 (25, 25, -325).

Formula

G.f.: (t^3 + 2*t^2 + 2*t + 1)/(325*t^3 - 25*t^2 - 25*t + 1)

Crossrefs

Sequence in context: A014914 A157461 A342037 * A163179 A163527 A164017

Adjacent sequences: A162824 A162825 A162826 * A162828 A162829 A162830

Keyword

nonn

Author

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

Status

approved