A161954 - OEIS

%I #5 Jul 19 2015 10:24:43

%S 1,27,377,3627,27026,166230,878409,4098483,17222607,66165501,

%T 235124461,780112671,2435132466,7196829486,20245295242,54455027238,

%U 140596223184,349621224120,839832229131,1953829030737,4412447681628,9693085025844

%N Number of reduced words of length n in the Weyl group B_27.

%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 II.)

%F 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.

%K nonn

%O 0,2

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