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A161476 Number of reduced words of length n in the Weyl group A_15. 0
1, 15, 119, 664, 2924, 10813, 34900, 100913, 266338, 650658, 1487262, 3208036, 6574987, 12876702, 24210652, 43874857, 76893687, 130701986, 216008661, 347854815, 546871981, 840732790, 1265769513, 1868715733, 2708503701 (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..24.

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: A331211 A183475 A253804 * A162321 A161875 A259746

Adjacent sequences:  A161473 A161474 A161475 * A161477 A161478 A161479

KEYWORD

nonn

AUTHOR

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

STATUS

approved

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Last modified November 26 03:20 EST 2020. Contains 338632 sequences. (Running on oeis4.)