A162186 Number of reduced words of length n in the Weyl group B_46.

1, 46, 1080, 17250, 210794, 2101418, 17796503, 131648504, 868101374, 5182032940, 28344317261, 143450494506, 677150551521, 3001361428036, 12561988338047, 49889607533966, 188796675237026, 683282982630926, 2372613717733406

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..18.

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: A035718 A246993 A161691 * A162452 A010998 A004424

Adjacent sequences: A162183 A162184 A162185 * A162187 A162188 A162189

Keyword

nonn

Author

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

Status

approved