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A162377 Number of reduced words of length n in the Weyl group D_30. 0
1, 30, 464, 4930, 40454, 273266, 1581775, 8064464, 36943940, 154385704, 595514217, 2140442150, 7224301969, 23043923160, 69844600965, 202081362622, 560350431315, 1494273031164, 3843681391300, 9562404542460, 23062890166272 (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..20.

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: A081736 A161573 A161976 * A162736 A010982 A022594

Adjacent sequences:  A162374 A162375 A162376 * A162378 A162379 A162380

KEYWORD

nonn

AUTHOR

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

STATUS

approved

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Last modified March 26 00:20 EDT 2019. Contains 321478 sequences. (Running on oeis4.)