

A162411


Number of reduced words of length n in the Weyl group D_42.


0



1, 42, 902, 13202, 148091, 1357468, 10587675, 72245074, 440091498, 2430433874, 12315996232, 57824666110, 253554446677, 1045266952884, 4073988274266, 15084671038416, 53281879968821, 180187334962466, 585265396834041
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OFFSET

0,2


COMMENTS

Computed with MAGMA using commands similar to those used to compute A161409.


REFERENCES

N. Bourbaki, Groupes et alg. de Lie, Chap. 4, 5, 6. (The group is defined in Planche IV.)
J. E. Humphreys, Reflection Groups and Coxeter Groups, Cambridge, 1990. See under PoincarĂ© polynomial.


LINKS

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


FORMULA

G.f. for D_m is the polynomial f(n) * Product( f(2i), i=1..n1 )/ f(1)^n, where f(k) = 1x^k. Only finitely many terms are nonzero. This is a row of the triangle in A162206.


CROSSREFS

Sequence in context: A296011 A161663 A162179 * A010994 A229564 A004422
Adjacent sequences: A162408 A162409 A162410 * A162412 A162413 A162414


KEYWORD

nonn


AUTHOR

John Cannon and N. J. A. Sloane, Dec 01 2009


STATUS

approved



