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A162204
Number of reduced words of length n in the Weyl group B_49.
0
1, 49, 1224, 20776, 269499, 2848811, 25555215, 200037215, 1394396185, 8790665065, 50733161116, 270672378844, 1345758869770, 6277354061930, 27627446293371, 115285643098059, 458048619713020, 1739199358769180
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 Poincaré polynomial.
N. Bourbaki, Groupes et alg. de Lie, Chap. 4, 5, 6. (The group is defined in Planche II.)
FORMULA
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.
CROSSREFS
Sequence in context: A017765 A163005 A161694 * A162469 A011001 A269418
KEYWORD
nonn
AUTHOR
John Cannon and N. J. A. Sloane, Nov 30 2009
STATUS
approved