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A165321
Number of reduced words of length n in Coxeter group on 17 generators S_i with relations (S_i)^2 = (S_i S_j)^9 = I.
0
1, 17, 272, 4352, 69632, 1114112, 17825792, 285212672, 4563402752, 73014443896, 1168231100160, 18691697567880, 299067160531200, 4785074559621120, 76561192811888640, 1224979082717429760, 19599665287114260480
OFFSET
0,2
COMMENTS
The initial terms coincide with those of A170736, although the two sequences are eventually different.
Computed with MAGMA using commands similar to those used to compute A154638.
FORMULA
G.f. (t^9 + 2*t^8 + 2*t^7 + 2*t^6 + 2*t^5 + 2*t^4 + 2*t^3 + 2*t^2 + 2*t +
1)/(120*t^9 - 15*t^8 - 15*t^7 - 15*t^6 - 15*t^5 - 15*t^4 - 15*t^3 -
15*t^2 - 15*t + 1)
MATHEMATICA
coxG[{9, 120, -15}] (* The coxG program is at A169452 *) (* Harvey P. Dale, Jan 31 2021 *)
CROSSREFS
Sequence in context: A163965 A164628 A164868 * A165879 A166411 A166585
KEYWORD
nonn
AUTHOR
John Cannon and N. J. A. Sloane, Dec 03 2009
STATUS
approved