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A162768 Number of reduced words of length n in Coxeter group on 13 generators S_i with relations (S_i)^2 = (S_i S_j)^3 = I. 0
1, 13, 156, 1794, 20592, 235950, 2703558, 30975516, 354897114, 4066164102, 46587289320, 533764778118, 6115505911086, 70067216486124, 802781471013522, 9197712172364430, 105380993789073288, 1207382188488922446 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

The initial terms coincide with those of A170732, 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..17.

Index entries for linear recurrences with constant coefficients, signature (11, 11, -66).

FORMULA

G.f.: (t^3 + 2*t^2 + 2*t + 1)/(66*t^3 - 11*t^2 - 11*t + 1)

CROSSREFS

Sequence in context: A192092 A297454 A102146 * A097827 A163084 A163438

Adjacent sequences:  A162765 A162766 A162767 * A162769 A162770 A162771

KEYWORD

nonn

AUTHOR

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

STATUS

approved

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Last modified August 23 22:20 EDT 2019. Contains 326254 sequences. (Running on oeis4.)