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A165690 Number of reduced words of length n in Coxeter group on 40 generators S_i with relations (S_i)^2 = (S_i S_j)^9 = I. 0
1, 40, 1560, 60840, 2372760, 92537640, 3608967960, 140749750440, 5489240267160, 214080370418460, 8349134446289520, 325616243404105680, 12699033492713883120, 495262306214038144080, 19315229942277159012720 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

The initial terms coincide with those of A170759, 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.

FORMULA

G.f. (t^9 + 2*t^8 + 2*t^7 + 2*t^6 + 2*t^5 + 2*t^4 + 2*t^3 + 2*t^2 + 2*t +

1)/(741*t^9 - 38*t^8 - 38*t^7 - 38*t^6 - 38*t^5 - 38*t^4 - 38*t^3 -

38*t^2 - 38*t + 1)

CROSSREFS

Sequence in context: A164085 A164684 A165172 * A166172 A166434 A166693

Adjacent sequences:  A165687 A165688 A165689 * A165691 A165692 A165693

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 June 19 14:08 EDT 2013. Contains 226411 sequences.