A161972 Number of reduced words of length n in the Weyl group B_29.

1, 29, 434, 4466, 35524, 232812, 1308509, 6482689, 28879476, 117441764, 441128513, 1544927933, 5083859819, 15819621191, 46800677805, 132236761657, 358269068693, 933922599849, 2349408360136, 5718723151160, 13500485623812

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 II.)

Links

Table of n, a(n) for n=0..20.

Formula

G.f. for B_m is the polynomial Prod_{k=1..m}(1-x^(2k))/(1-x). Only finitely many terms are nonzero. This is a row of the triangle in A128084.

Crossrefs

Sequence in context: A163021 A125464 A161572 * A162376 A188356 A162732

Adjacent sequences: A161969 A161970 A161971 * A161973 A161974 A161975

Keyword

nonn

Author

John Cannon and N. J. A. Sloane, Nov 30 2009

Status

approved