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 A165216 #9 Nov 23 2016 22:07:08
%S A165216 1,9,72,576,4608,36864,294912,2359296,18874368,150994908,1207958976,
%T A165216 9663669540,77309338176,618474560256,4947795320832,39582353276928,
%U A165216 316658751897600,2533269420638208,20266150608766188,162129166819422768
%N A165216 Number of reduced words of length n in Coxeter group on 9 generators S_i with relations (S_i)^2 = (S_i S_j)^9 = I.
%C A165216 The initial terms coincide with those of A003951, although the two sequences are eventually different.
%C A165216 Computed with MAGMA using commands similar to those used to compute A154638.
%H A165216 <a href="/index/Rec#order_09">Index entries for linear recurrences with constant coefficients</a>, signature (7, 7, 7, 7, 7, 7, 7, 7, -28).
%F A165216 G.f. (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 +
%F A165216 1)/(28*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
%F A165216 + 1)
%t A165216 With[{num=Total[2t^Range[8]]+t^9+1,den=Total[-7 t^Range[8]]+ 28t^9+1}, CoefficientList[Series[num/den,{t,0,30}],t]] (* _Harvey P. Dale_, Oct 02 2011 *)
%K A165216 nonn
%O A165216 0,2
%A A165216 _John Cannon_ and _N. J. A. Sloane_, Dec 03 2009