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A162248
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Number of reduced words of length n in the Weyl group D_10.
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0
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1, 10, 54, 210, 659, 1772, 4235, 9218, 18590, 35178, 63063, 107900, 177243, 280850, 430939, 642364, 932680, 1322068, 1833095, 2490290, 3319525, 4347200, 5599243, 7099950, 8870703, 10928616, 13285169, 15944898, 18904214, 22150426, 25661040
(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
| 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 Poincare polynomial.
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FORMULA
| G.f. for D_m is the polynomial f(n) * Product( f(2i), i=1..n-1 )/ f(1)^n, where f(k) = 1-x^k. Only finitely many terms are nonzero. This is a row of the triangle in A162206.
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CROSSREFS
| Sequence in context: A093187 A152762 A161458 * A161755 A053347 A036600
Adjacent sequences: A162245 A162246 A162247 * A162249 A162250 A162251
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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), Dec 01 2009
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