

A161530


Number of reduced words of length n in the Weyl group A_27.


0



1, 27, 377, 3626, 26999, 165852, 874755, 4071079, 17052724, 65259715, 230856472, 761987905, 2364726003, 6943746516, 19395654894, 51770913911, 132567002957, 326758146932, 777583981286, 1791153918119, 4003030425506, 8697839966552
(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..21.


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: A110207 A223205 A257786 * A161954 A162369 A231858
Adjacent sequences: A161527 A161528 A161529 * A161531 A161532 A161533


KEYWORD

nonn


AUTHOR

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


STATUS

approved



