A162193 Number of reduced words of length n in the Weyl group B_48.

1, 48, 1175, 19552, 248723, 2579312, 22706404, 174482000, 1194358970, 7396268880, 41942496051, 219939217728, 1075086490926, 4931595192160, 21350092231441, 87658196804688, 342762976614961, 1281150739056160

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..17.

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: A035797 A213442 A161693 * A162461 A344401 A369561

Adjacent sequences: A162190 A162191 A162192 * A162194 A162195 A162196

Keyword

nonn

Author

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

Status

approved