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A164860 Number of reduced words of length n in Coxeter group on 15 generators S_i with relations (S_i)^2 = (S_i S_j)^8 = I. 0
1, 15, 210, 2940, 41160, 576240, 8067360, 112943040, 1581202455, 22136832900, 309915640125, 4338818675100, 60743457438300, 850408347952800, 11905716084771600, 166680014174856000, 2333520044280745320 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

The initial terms coincide with those of A170734, 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.

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)/(91*t^8 -

13*t^7 - 13*t^6 - 13*t^5 - 13*t^4 - 13*t^3 - 13*t^2 - 13*t + 1)

CROSSREFS

Sequence in context: A163440 A163962 A164626 * A165282 A165875 A166382

Adjacent sequences:  A164857 A164858 A164859 * A164861 A164862 A164863

KEYWORD

nonn

AUTHOR

John Cannon (john(AT)maths.usyd.edu.au) and N. J. A. Sloane, Dec 03 2009

STATUS

approved

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Last modified May 20 01:11 EDT 2013. Contains 225445 sequences.