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A163091 Number of reduced words of length n in Coxeter group on 15 generators S_i with relations (S_i)^2 = (S_i S_j)^4 = I. 0
1, 15, 210, 2940, 41055, 573300, 8005725, 111793500, 1561106820, 21799608285, 304414090890, 4250899269435, 59360407871310, 828920611657320, 11575213262103855, 161638593827703720, 2257153663002754425 (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.

Index entries for linear recurrences with constant coefficients, signature (13, 13, 13, -91).

FORMULA

G.f.: (t^4 + 2*t^3 + 2*t^2 + 2*t + 1)/(91*t^4 - 13*t^3 - 13*t^2 - 13*t + 1)

CROSSREFS

Sequence in context: A000483 A162785 A076139 * A163440 A163962 A164626

Adjacent sequences:  A163088 A163089 A163090 * A163092 A163093 A163094

KEYWORD

nonn

AUTHOR

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

STATUS

approved

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Last modified August 25 13:50 EDT 2019. Contains 326324 sequences. (Running on oeis4.)