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, 30975333122308, 69200799829694, 150787694622966

Offset: 0

Author

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

Keywords

• nonn
• fini
• full

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

• Andrew Howroyd, Table of n, a(n) for n = 0..841

Crossrefs

Row n=29 of A128084.

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.