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A161497 Number of reduced words of length n in the Weyl group A_17. 1
1, 17, 152, 951, 4674, 19210, 68646, 218995, 635682, 1703027, 4257634, 10020277, 22357907, 47572239, 96997223, 190297064, 360490592, 661386105, 1178290263, 2043049102, 3454679139, 5707038378, 9225153393, 14611938428, 22707091351 (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.
LINKS
Robert Israel, Table of n, a(n) for n = 0..153 (complete sequence)
N. Bourbaki, Groupes et algèbres de Lie, Chap. 4, 5, 6. (The group is defined in Planche I.)
FORMULA
G.f. for A_m is the polynomial Product_{k=1..m}(1-x^(k+1))/(1-x). Only finitely many terms are nonzero. This is a row of the triangle in A008302.
MAPLE
G:= normal(mul((1-x^(k+1))/(1-x), k=1..17)):
seq(coeff(G, x, j), j=0..17*18/2); # Robert Israel, Mar 28 2017
CROSSREFS
Sequence in context: A299599 A244852 A064102 * A162328 A161877 A221737
KEYWORD
nonn,fini,full
AUTHOR
John Cannon and N. J. A. Sloane, Nov 30 2009
STATUS
approved

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Last modified March 2 08:00 EST 2024. Contains 370461 sequences. (Running on oeis4.)