A161862 Number of reduced words of length n in the Weyl group B_14.

1, 14, 104, 546, 2274, 7994, 24647, 68392, 173978, 411332, 913445, 1921218, 3852849, 7407596, 13716315, 24553998, 42632552, 71995170, 118536730, 190677578, 300220648, 463423974, 702322075, 1046330260, 1534165425

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..24.

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: A089508 A161475 A162301 * A266561 A370962 A222369

Adjacent sequences: A161859 A161860 A161861 * A161863 A161864 A161865

Keyword

nonn

Author

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

Status

approved