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A162182
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Number of reduced words of length n in the Weyl group B_44.
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0
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1, 44, 989, 15136, 177374, 1697080, 13804461, 98156916, 622600869, 3577478696, 18848352755, 91943892924, 418593879770, 1790510819500, 7236416033496, 27766992285908, 101579448507141, 355579239690840, 1194844427708580
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| Computed with MAGMA using commands similar to those used to compute A161409.
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REFERENCES
| J. E. Humphreys, Reflection Groups and Coxeter Groups, Cambridge, 1990. See under Poincare polynomial.
N. Bourbaki, Groupes et alg. de Lie, Chap. 4, 5, 6. (The group is defined in Planche II.)
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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.
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CROSSREFS
| Sequence in context: A035611 A161679 * A162413 A010996 A004423 A172978
Adjacent sequences: A162179 A162180 A162181 * A162183 A162184 A162185
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KEYWORD
| nonn
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AUTHOR
| John Cannon (john(AT)maths.usyd.edu.au) and N. J. A. Sloane (njas(AT)research.att.com), Nov 30 2009
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