A161653 - OEIS

%I #5 Jul 19 2015 10:30:10

%S 1,40,819,11439,122549,1073668,8009350,52303783,305103058,1614351753,

%T 7841707642,35308785736,148545224987,587774258402,2199717843602,

%U 7823584303472,26553558780617,86314483678430,269565581279715

%N Number of reduced words of length n in the Weyl group A_40.

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

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

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

%F 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.

%K nonn

%O 0,2

%A _John Cannon_ and _N. J. A. Sloane_, Nov 30 2009