A165178 - OEIS

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A165178

Number of reduced words of length n in Coxeter group on 46 generators S_i with relations (S_i)^2 = (S_i S_j)^8 = I.

1, 46, 2070, 93150, 4191750, 188628750, 8488293750, 381973218750, 17188794842715, 773495767875600, 34807309552307160, 1566328929759554400, 70484801834937897000, 3171816082381313070000, 142731723698568934875000

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OFFSET

0,2

COMMENTS

The initial terms coincide with those of A170765, 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 (44, 44, 44, 44, 44, 44, 44, -990).

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)/(990*t^8 -

44*t^7 - 44*t^6 - 44*t^5 - 44*t^4 - 44*t^3 - 44*t^2 - 44*t + 1)

CROSSREFS

Sequence in context: A163802 A164331 A164691 * A165702 A166303 A166440

Adjacent sequences: A165175 A165176 A165177 * A165179 A165180 A165181

KEYWORD

nonn

AUTHOR

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

STATUS

approved