This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A166366 #12 Mar 13 2020 08:38:33
%S A166366 1,8,56,392,2744,19208,134456,941192,6588344,46118408,322828856,
%T A166366 2259801964,15818613552,110730293520,775112045232,5425784250768,
%U A166366 37980489294384,265863421833744,1861043930247600,13027307353612944
%N A166366 Number of reduced words of length n in Coxeter group on 8 generators S_i with relations (S_i)^2 = (S_i S_j)^11 = I.
%C A166366 The initial terms coincide with those of A003950, although the two sequences are eventually different.
%C A166366 Computed with MAGMA using commands similar to those used to compute A154638.
%H A166366 G. C. Greubel, <a href="/A166366/b166366.txt">Table of n, a(n) for n = 0..500</a>
%H A166366 <a href="/index/Rec#order_11">Index entries for linear recurrences with constant coefficients</a>, signature (6,6,6,6,6,6,6,6,6,6,-21).
%F A166366 G.f.: (t^11 + 2*t^10 + 2*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)/(21*t^11 - 6*t^10 - 6*t^9 - 6*t^8 - 6*t^7 - 6*t^6 - 6*t^5 - 6*t^4 - 6*t^3 - 6*t^2 - 6*t + 1).
%p A166366 seq(coeff(series((1+t)*(1-t^11)/(1-7*t+27*t^11-21*t^12), t, n+1), t, n), n = 0 .. 30); # _G. C. Greubel_, Mar 13 2020
%t A166366 CoefficientList[Series[(1+t)*(1-t^11)/(1-7*t+27*t^11-21*t^12), {t,0,30}], t] (* _G. C. Greubel_, May 10 2016 *)
%t A166366 coxG[{11, 21, -6}] (* The coxG program is in A169452 *) (* _G. C. Greubel_, Mar 13 2020 *)
%o A166366 (Sage)
%o A166366 def A166366_list(prec):
%o A166366 P.<t> = PowerSeriesRing(ZZ, prec)
%o A166366 return P( (1+t)*(1-t^11)/(1-7*t+27*t^11-21*t^12) ).list()
%o A166366 A166366_list(30) # _G. C. Greubel_, Mar 13 2020
%K A166366 nonn
%O A166366 0,2
%A A166366 _John Cannon_ and _N. J. A. Sloane_, Dec 03 2009