

A162166


Number of reduced words of length n in the Weyl group B_38.


0



1, 38, 740, 9842, 100528, 840750, 5994443, 37460020, 209355471, 1062545094, 4956417103, 21455163508, 86870115631, 331163611782, 1195264474584, 4103926538058, 13459612095894, 42317155173498, 127942640917705
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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 II.)


LINKS

Table of n, a(n) for n=0..18.


FORMULA

G.f. for B_m is the polynomial Prod_{k=1..m}(1x^(2k))/(1x). Only finitely many terms are nonzero. This is a row of the triangle in A128084.


CROSSREFS

Sequence in context: A010954 A035714 A161651 * A162392 A010990 A004420
Adjacent sequences: A162163 A162164 A162165 * A162167 A162168 A162169


KEYWORD

nonn


AUTHOR

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


STATUS

approved



