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Search: id:A162183
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| A162183 |
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Number of reduced words of length n in the Weyl group B_45. |
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+0
1
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| 1, 45, 1034, 16170, 193544, 1890624, 15695085, 113852001, 736452870, 4313931566, 23162284321, 115106177245, 533700057015, 2324210876515, 9560626910011, 37327619195919, 138907067703060, 494486307393900, 1689330735102480
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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Computed with MAGMA using commands similar to those used to compute A161409.
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REFERENCES
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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
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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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KEYWORD
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nonn,new
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AUTHOR
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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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