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A163171
Number of reduced words of length n in Coxeter group on 23 generators S_i with relations (S_i)^2 = (S_i S_j)^4 = I.
0
1, 23, 506, 11132, 244651, 5376756, 118166433, 2596973148, 57074328696, 1254336803181, 27566873759502, 605844081921771, 13314786972244758, 292622404684911840, 6431035802682200787, 141336482898202575984
OFFSET
0,2
COMMENTS
The initial terms coincide with those of A170742, 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)/(231*t^4 - 21*t^3 - 21*t^2 - 21*t + 1).
MATHEMATICA
CoefficientList[Series[(t^4 + 2 t^3 + 2 t^2 + 2 t + 1)/(231 t^4 - 21 t^3 - 21 t^2 - 21 t + 1), {t, 0, 20}], t] (* Jinyuan Wang, Mar 23 2020 *)
CROSSREFS
Sequence in context: A121903 A162809 A212336 * A163518 A163991 A164636
KEYWORD
nonn
AUTHOR
John Cannon and N. J. A. Sloane, Dec 03 2009
STATUS
approved