

A161933


Number of reduced words of length n in the Weyl group B_26.


0



1, 26, 350, 3250, 23399, 139204, 712179, 3220074, 13124124, 48942894, 168958960, 544988210, 1655019795, 4761697020, 13048465756, 34209731996, 86141195946, 209025000936, 490211005011, 1113996801606, 2458618650891, 5280637344216
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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..21.


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: A053494 A054938 A161526 * A162368 A225979 A162718
Adjacent sequences: A161930 A161931 A161932 * A161934 A161935 A161936


KEYWORD

nonn


AUTHOR

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


STATUS

approved



