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A162949
Number of reduced words of length n in Coxeter group on 8 generators S_i with relations (S_i)^2 = (S_i S_j)^4 = I.
0
1, 8, 56, 392, 2716, 18816, 130368, 903168, 6257076, 43348536, 300314952, 2080556856, 14413923468, 99858452400, 691810982352, 4792808455344, 33204174947748, 230035738812264, 1593668302662744, 11040800320974312
OFFSET
0,2
COMMENTS
The initial terms coincide with those of A003950, although the two sequences are eventually different.
Computed with MAGMA using commands similar to those used to compute A154638.
FORMULA
G.f.: (t^4 + 2*t^3 + 2*t^2 + 2*t + 1)/(21*t^4 - 6*t^3 - 6*t^2 - 6*t + 1)
MATHEMATICA
coxG[{4, 21, -6}] (* The coxG program is at A169452 *) (* Harvey P. Dale, May 04 2018 *)
CROSSREFS
Sequence in context: A214942 A010556 A010575 * A063812 A234274 A163347
KEYWORD
nonn
AUTHOR
John Cannon and N. J. A. Sloane, Dec 03 2009
STATUS
approved