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, 2216115226, 3156684454, 4437642874, 6161492611, 8455365296

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..196

Crossrefs

Row n=14 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.