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A162328 Number of reduced words of length n in the Weyl group D_17. 0
1, 17, 152, 952, 4691, 19363, 69615, 223839, 656013, 1777469, 4501652, 10749780, 24374702, 52784014, 109694031, 219658751, 425310726, 798645125, 1458198664, 2594648817, 4508215686, 7662320971, 12759278753, 20845394645, 33454765680 (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

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

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

LINKS

Table of n, a(n) for n=0..24.

FORMULA

G.f. for D_m is the polynomial f(n) * Product( f(2i), i=1..n-1 )/ f(1)^n, where f(k) = 1-x^k. Only finitely many terms are nonzero. This is a row of the triangle in A162206.

CROSSREFS

Sequence in context: A244852 A064102 A161497 * A161877 A221737 A139617

Adjacent sequences:  A162325 A162326 A162327 * A162329 A162330 A162331

KEYWORD

nonn

AUTHOR

John Cannon and N. J. A. Sloane, Dec 01 2009

STATUS

approved

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Last modified October 19 14:21 EDT 2018. Contains 316362 sequences. (Running on oeis4.)