login
A161459
Number of reduced words of length n in the Weyl group A_11.
0
1, 11, 65, 274, 923, 2640, 6655, 15159, 31758, 61997, 113906, 198497, 330121, 526581, 808896, 1200626, 1726701, 2411747, 3277965, 4342688, 5615807, 7097310, 8775209, 10624132, 12604826, 14664752, 16739858, 18757500, 20640357, 22311069
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: A215445 A184055 A332750 * A162288 A161776 A054333
KEYWORD
nonn
AUTHOR
John Cannon and N. J. A. Sloane, Nov 30 2009
STATUS
approved