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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 (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 Poincaré 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}(1-x^(2k))/(1-x). 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

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Last modified August 8 13:57 EDT 2020. Contains 336298 sequences. (Running on oeis4.)