A161694 Number of reduced words of length n in the Weyl group A_49.

1, 49, 1224, 20775, 269450, 2847586, 25534390, 199766491, 1391526550, 8764839175, 50530255490, 269252177545, 1336765568579, 6225203548375, 27347806169775, 113887933772724, 451493020193130, 1710182996663175

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 I.)

Links

Table of n, a(n) for n=0..17.

Formula

G.f. for A_m is the polynomial Prod_{k=1..m}(1-x^(k+1))/(1-x). Only finitely many terms are nonzero. This is a row of the triangle in A008302.

Crossrefs

Sequence in context: A173246 A017765 A163005 * A162204 A162469 A011001

Adjacent sequences: A161691 A161692 A161693 * A161695 A161696 A161697

Keyword

nonn

Author

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

Status

approved