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A162456 Number of reduced words of length n in the Weyl group D_47. 0
1, 47, 1127, 18377, 229171, 2330589, 20127092, 151775596, 1019876970, 6201909910, 34546227171, 177996721677, 855147273198, 3856508701234, 16418497039281, 66308104573247, 255104779810273, 938387762441199 (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..17.

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: A234354 A161692 A162191 * A010999 A182019 A270501

Adjacent sequences:  A162453 A162454 A162455 * A162457 A162458 A162459

KEYWORD

nonn

AUTHOR

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

STATUS

approved

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Last modified March 30 06:59 EDT 2020. Contains 333119 sequences. (Running on oeis4.)