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A161461
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Number of reduced words of length n in the Weyl group A_12.
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0
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1, 12, 77, 351, 1274, 3914, 10569, 25728, 57486, 119483, 233389, 431886, 762007, 1288587, 2097472, 3298033, 5024460, 7435284, 10710609, 15046642, 20647290, 27712842, 36426054, 46936280, 59342609, 73677240, 89890517, 107839121
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OFFSET
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0,2
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COMMENTS
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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 Poincaré polynomial.
N. Bourbaki, Groupes et alg. de Lie, Chap. 4, 5, 6. (The group is defined in Planche I.)
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LINKS
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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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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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