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 A166859 #9 Nov 24 2016 10:23:25
%S A166859 1,5,20,80,320,1280,5120,20480,81920,327680,1310720,5242880,20971520,
%T A166859 83886070,335544240,1342176810,5368706640,21474824160,85899287040,
%U A166859 343597109760,1374388285440,5497552527360,21990207651840,87960820776960
%N A166859 Number of reduced words of length n in Coxeter group on 5 generators S_i with relations (S_i)^2 = (S_i S_j)^13 = I.
%C A166859 The initial terms coincide with those of A003947, although the two sequences are eventually different.
%C A166859 Computed with MAGMA using commands similar to those used to compute A154638.
%H A166859 G. C. Greubel, <a href="/A166859/b166859.txt">Table of n, a(n) for n = 0..1000</a>
%H A166859 <a href="/index/Rec#order_13">Index entries for linear recurrences with constant coefficients</a>, signature (3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, -6).
%F A166859 G.f.: (t^13 + 2*t^12 + 2*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)/(6*t^13 - 3*t^12 - 3*t^11 - 3*t^10 - 3*t^9 - 3*t^8 - 3*t^7 - 3*t^6 - 3*t^5 - 3*t^4 - 3*t^3 - 3*t^2 - 3*t + 1).
%t A166859 CoefficientList[Series[(t^13 + 2*t^12 + 2*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)/(6*t^13 - 3*t^12 - 3*t^11 - 3*t^10 - 3*t^9 - 3*t^8 - 3*t^7 - 3*t^6 - 3*t^5 - 3*t^4 - 3*t^3 - 3*t^2 - 3*t + 1), {t, 0, 50}], t] (* _G. C. Greubel_, May 25 2016 *)
%K A166859 nonn
%O A166859 0,2
%A A166859 _John Cannon_ and _N. J. A. Sloane_, Dec 03 2009