|
| |
|
|
A161465
|
|
Number of reduced words of length n in the Weyl group A_13.
|
|
0
| |
|
|
1, 13, 90, 441, 1715, 5629, 16198, 41926, 99412, 218895, 452284, 884170, 1646177, 2934764, 5032235, 8330256, 13354639, 20789572, 31498907, 46541635, 67178356, 94865470, 131234038, 178050835, 237160055, 310405409, 399533919, 506084453
(list; graph; refs; listen; history; 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 Poincare polynomial.
N. Bourbaki, Groupes et alg. de Lie, Chap. 4, 5, 6. (The group is defined in Planche I.)
|
|
|
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: A082099 A152867 A026912 * A162300 A161859 A057788
Adjacent sequences: A161462 A161463 A161464 * A161466 A161467 A161468
|
|
|
KEYWORD
| nonn
|
|
|
AUTHOR
| John Cannon (john(AT)maths.usyd.edu.au) and N. J. A. Sloane (njas(AT)research.att.com), Nov 30 2009
|
| |
|
|
