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A161525
Number of reduced words of length n in the Weyl group A_25.
0
1, 25, 324, 2899, 20124, 115480, 570050, 2487421, 9785321, 35225346, 117389766, 365534676, 1071606665, 2976282415, 7872887865, 19923350639, 48420830029, 113395054929, 256634690379, 562744102479, 1198306570554, 2482933033659
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.)
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: A250559 A244446 A246625 * A161932 A162367 A263404
KEYWORD
nonn
AUTHOR
John Cannon and N. J. A. Sloane, Nov 30 2009
STATUS
approved