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A161649
Number of reduced words of length n in the Weyl group A_36.
0
1, 36, 665, 8399, 81548, 648870, 4405035, 26229634, 139771903, 676798487, 3013713196, 12459957237, 48208023941, 175693594055, 606498724614, 1992486365264, 6254976819720, 18830657260788, 54534379879411
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 I.)
J. E. Humphreys, Reflection Groups and Coxeter Groups, Cambridge, 1990. See under Poincaré polynomial.
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: A231767 A278277 A188305 * A162150 A162388 A010988
KEYWORD
nonn
AUTHOR
John Cannon and N. J. A. Sloane, Nov 30 2009
STATUS
approved