

A162388


Number of reduced words of length n in the Weyl group D_36.


0



1, 36, 665, 8400, 81584, 649536, 4413471, 26311884, 140429874, 681294172, 3040682386, 12604874396, 48916205718, 178878544028, 619807366651, 2044561200672, 6447023494362, 19501857519768, 56767942666603
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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: A188305 A161649 A162150 * A010988 A000815 A271794
Adjacent sequences: A162385 A162386 A162387 * A162389 A162390 A162391


KEYWORD

nonn


AUTHOR

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


STATUS

approved



