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A161652 Number of reduced words of length n in the Weyl group A_39. 0
1, 39, 779, 10620, 111110, 951119, 6935682, 44294433, 252799275, 1309248695, 6227355889, 27467078094, 113236439251, 439229033415, 1611943585200, 5623866459870, 18729974477145, 59760924897813, 183251097601285 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Computed with MAGMA using commands similar to those used to compute A161409.

REFERENCES

J. E. Humphreys, Reflection Groups and Coxeter Groups, Cambridge, 1990. See under Poincaré polynomial.

N. Bourbaki, Groupes et alg. de Lie, Chap. 4, 5, 6. (The group is defined in Planche I.)

LINKS

Table of n, a(n) for n=0..18.

FORMULA

G.f. for A_m is the polynomial Prod_{k=1..m}(1-x^(k+1))/(1-x). Only finitely many terms are nonzero. This is a row of the triangle in A008302.

CROSSREFS

Sequence in context: A034187 A059609 A010955 * A162168 A162399 A126927

Adjacent sequences:  A161649 A161650 A161651 * A161653 A161654 A161655

KEYWORD

nonn

AUTHOR

John Cannon and N. J. A. Sloane, Nov 30 2009

STATUS

approved

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Last modified April 24 12:21 EDT 2019. Contains 322429 sequences. (Running on oeis4.)