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 A166367 #15 Mar 13 2020 20:48:48
%S A166367 1,9,72,576,4608,36864,294912,2359296,18874368,150994944,1207959552,
%T A166367 9663676380,77309410752,618475283748,4947802251840,39582417869568,
%U A166367 316659341795328,2533274725072896,20266197726265344,162129581215580160
%N A166367 Number of reduced words of length n in Coxeter group on 9 generators S_i with relations (S_i)^2 = (S_i S_j)^11 = I.
%C A166367 The initial terms coincide with those of A003951, although the two sequences are eventually different.
%C A166367 Computed with MAGMA using commands similar to those used to compute A154638.
%H A166367 G. C. Greubel, <a href="/A166367/b166367.txt">Table of n, a(n) for n = 0..500</a>
%H A166367 <a href="/index/Rec#order_11">Index entries for linear recurrences with constant coefficients</a>, signature (7,7,7,7,7,7,7,7,7,7,-28).
%F A166367 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)/(28*t^11 - 7*t^10 - 7*t^9 - 7*t^8 - 7*t^7 - 7*t^6 - 7*t^5 - 7*t^4 - 7*t^3 - 7*t^2 - 7*t + 1).
%p A166367 seq(coeff(series((1+t)*(1-t^11)/(1-8*t+35*t^11-28*t^12), t, n+1), t, n), n = 0 .. 30); # _G. C. Greubel_, Mar 13 2020
%t A166367 CoefficientList[Series[(1+t)*(1-t^11)/(1-8*t+35*t^11-28*t^12), {t,0,30}], t] (* _G. C. Greubel_, May 10 2016 *)
%t A166367 coxG[{11,28,-7}] (* The coxG program is at A169452 *) (* _Harvey P. Dale_, Jun 07 2019 *)
%o A166367 (Sage)
%o A166367 def A166367_list(prec):
%o A166367 P.<t> = PowerSeriesRing(ZZ, prec)
%o A166367 return P( (1+t)*(1-t^11)/(1-8*t+35*t^11-28*t^12) ).list()
%o A166367 A166367_list(30) # _G. C. Greubel_, Mar 13 2020
%K A166367 nonn
%O A166367 0,2
%A A166367 _John Cannon_ and _N. J. A. Sloane_, Dec 03 2009