A161573 Number of reduced words of length n in the Weyl group A_30.

1, 30, 464, 4929, 40424, 272801, 1576815, 8023545, 36665715, 152763040, 587171992, 2101880476, 7061614495, 22410120565, 67543053580, 194231327451, 535041945135, 1416733053564, 3616888634024, 8926662604634, 21349085390900

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..20.

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: A281700 A024524 A081736 * A161976 A162377 A162736

Adjacent sequences: A161570 A161571 A161572 * A161574 A161575 A161576

Keyword

nonn

Author

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

Status

approved