A162150 Number of reduced words of length n in the Weyl group B_36.

1, 36, 665, 8400, 81584, 649536, 4413471, 26311884, 140429874, 681294172, 3040682386, 12604874396, 48916205718, 178878544028, 619807366651, 2044561200672, 6447023494362, 19501857519768, 56767942666603

Offset

0,2

Comments

Computed with MAGMA using commands similar to those used to compute A161409.

References

N. Bourbaki, Groupes et alg. de Lie, Chap. 4, 5, 6. (The group is defined in Planche II.)

J. E. Humphreys, Reflection Groups and Coxeter Groups, Cambridge, 1990. See under Poincaré polynomial.

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: A278277 A188305 A161649 * A162388 A010988 A000815

Adjacent sequences: A162147 A162148 A162149 * A162151 A162152 A162153

Keyword

nonn

Author

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

Status

approved