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A166327 Number of reduced words of length n in Coxeter group on 3 generators S_i with relations (S_i)^2 = (S_i S_j)^11 = I. 1
1, 3, 6, 12, 24, 48, 96, 192, 384, 768, 1536, 3069, 6132, 12255, 24492, 48948, 97824, 195504, 390720, 780864, 1560576, 3118848, 6233094, 12456993, 24895608, 49754487, 99435570, 198724440, 397155696, 793725456, 1586279904, 3170219520 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,2
COMMENTS
The initial terms coincide with those of A003945, although the two sequences are eventually different.
Computed with MAGMA using commands similar to those used to compute A154638.
LINKS
FORMULA
G.f.: (t^10 + t^9 + t^8 + t^7 + t^6 + t^5 + t^4 + t^3 + t^2 + t + 1) / (t^10 - 2*t^9 + t^8 - 2*t^7 + t^6 - 2*t^5 + t^4 - 2*t^3 + t^2 - 2*t + 1).
MAPLE
seq(coeff(series((1+t)*(1-t^11)/(1-2*t+2*t^11-t^12), t, n+1), t, n), n = 0..30); # G. C. Greubel, Mar 12 2020
MATHEMATICA
CoefficientList[Series[(1+t)*(1-t^11)/(1-2*t+2*t^11-t^12), {t, 0, 30}], t] (* G. C. Greubel, May 09 2016 *)
PROG
(Sage)
def A166327_list(prec):
P.<t> = PowerSeriesRing(ZZ, prec)
return P( (1+t)*(1-t^11)/(1-2*t+2*t^11-t^12) ).list()
A166327_list(30) # G. C. Greubel, Aug 10 2019
CROSSREFS
Sequence in context: A165183 A046944 A165745 * A166467 A166857 A364496
KEYWORD
nonn
AUTHOR
John Cannon and N. J. A. Sloane, Dec 03 2009
STATUS
approved

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Last modified March 28 22:04 EDT 2024. Contains 371254 sequences. (Running on oeis4.)