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 A161499 Number of reduced words of length n in the Weyl group A_18. 0
 1, 18, 170, 1121, 5795, 25005, 93651, 312646, 948328, 2651355, 6908989, 16929266, 39287173, 86859412, 183856635, 374153699, 734644291, 1396030396, 2574320659, 4617369760, 8072048882, 13779087108, 23004239550, 37616173304, 60323245445 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Computed with MAGMA using commands similar to those used to compute A161409. REFERENCES 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.) LINKS 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. CROSSREFS Sequence in context: A125381 A126539 A213802 * A162346 A161878 A139618 Adjacent sequences: A161496 A161497 A161498 * A161500 A161501 A161502 KEYWORD nonn AUTHOR John Cannon and N. J. A. Sloane, Nov 30 2009 STATUS approved

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Last modified March 26 17:26 EDT 2023. Contains 361551 sequences. (Running on oeis4.)