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A164892 Number of reduced words of length n in Coxeter group on 18 generators S_i with relations (S_i)^2 = (S_i S_j)^8 = I. 0
1, 18, 306, 5202, 88434, 1503378, 25557426, 434476242, 7386095961, 125563628736, 2134581644448, 36287887206528, 616894069776480, 10487198969713728, 178282378804864032, 3030800377118109696, 51523605347410047672 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

The initial terms coincide with those of A170737, 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..16.

Index entries for linear recurrences with constant coefficients, signature (16, 16, 16, 16, 16, 16, 16, -136).

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)/(136*t^8 -

16*t^7 - 16*t^6 - 16*t^5 - 16*t^4 - 16*t^3 - 16*t^2 - 16*t + 1)

CROSSREFS

Sequence in context: A163452 A163967 A164630 * A165329 A165880 A166412

Adjacent sequences:  A164889 A164890 A164891 * A164893 A164894 A164895

KEYWORD

nonn

AUTHOR

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

STATUS

approved

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Last modified June 16 05:18 EDT 2019. Contains 324145 sequences. (Running on oeis4.)