A161976 Number of reduced words of length n in the Weyl group B_30.

1, 30, 464, 4930, 40454, 273266, 1581775, 8064464, 36943940, 154385704, 595514217, 2140442150, 7224301969, 23043923160, 69844600965, 202081362622, 560350431315, 1494273031164, 3843681391300, 9562404542460, 23062890166272, 54038223288580, 123239023118274, 274026717741240

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

Andrew Howroyd, Table of n, a(n) for n = 0..900

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

Row n=30 of A128084.

Sequence in context: A024524 A081736 A161573 * A162377 A162736 A010982

Adjacent sequences: A161973 A161974 A161975 * A161977 A161978 A161979

Keyword

nonn,fini,full

Author

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

Status

approved