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A161668
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Number of reduced words of length n in the Weyl group A_43.
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0
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1, 43, 945, 14146, 162195, 1518760, 12093191, 84189271, 522910058, 2942607305, 15184988654, 72558839841, 323609385853, 1356110885092, 5369781181160, 20188204577529, 72364939854816, 248214470691451, 817302378367149
(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 I.)
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FORMULA
| G.f. for A_m is the polynomial Prod_{k=1..m}(1-x^(k+1))/(1-x). Only finitely many terms are nonzero. This is a row of the triangle in A008302.
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CROSSREFS
| Sequence in context: A146979 A157722 A010959 * A162181 A162412 A010995
Adjacent sequences: A161665 A161666 A161667 * A161669 A161670 A161671
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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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