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Search: id:A161690
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| A161690 |
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Number of reduced words of length n in the Weyl group A_45. |
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+0
1
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| 1, 45, 1034, 16169, 193499, 1889589, 15678870, 113657422, 734546032, 4298041947, 23046526516, 114353850926, 529270561189, 2300298156544, 9441106933059, 36770120287103, 136464073495963, 484372497396274, 1649583299663734
(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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N. Bourbaki, Groupes et alg. de Lie, Chap. 4, 5, 6. (The group is defined in Planche I.)
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FORMULA
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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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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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