

A161663


Number of reduced words of length n in the Weyl group A_42.


0



1, 42, 902, 13201, 148049, 1356565, 10574431, 72096080, 438720787, 2419697247, 12242381349, 57373851187, 251050546012, 1032501499239, 4013670296068, 14818423396369, 52176735277287, 175849530836635, 569087907675698
(list;
graph;
refs;
listen;
history;
text;
internal format)



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 PoincarĂ© 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..18.


FORMULA

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


CROSSREFS

Sequence in context: A010958 A035716 A296011 * A162179 A162411 A010994
Adjacent sequences: A161660 A161661 A161662 * A161664 A161665 A161666


KEYWORD

nonn


AUTHOR

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


STATUS

approved



