A165182 Number of reduced words of length n in Coxeter group on 50 generators S_i with relations (S_i)^2 = (S_i S_j)^8 = I.

1, 50, 2450, 120050, 5882450, 288240050, 14123762450, 692064360050, 33911153641225, 1661646528360000, 81420679886700000, 3989613314304240000, 195491052393848820000, 9579061566952704120000, 469374016763733986940000

Offset

0,2

Comments

The initial terms coincide with those of A170769, 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..14.

Index entries for linear recurrences with constant coefficients, signature (48, 48, 48, 48, 48, 48, 48, -1176).

Formula

G.f. (t^8 + 2*t^7 + 2*t^6 + 2*t^5 + 2*t^4 + 2*t^3 + 2*t^2 + 2*t + 1)/(1176*t^8 -

48*t^7 - 48*t^6 - 48*t^5 - 48*t^4 - 48*t^3 - 48*t^2 - 48*t + 1)

Crossrefs

Sequence in context: A163837 A164351 A164695 * A165726 A166325 A166463

Adjacent sequences: A165179 A165180 A165181 * A165183 A165184 A165185

Keyword

nonn

Author

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

Status

approved