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 A168974 #10 Nov 25 2016 10:21:10
%S A168974 1,9,72,576,4608,36864,294912,2359296,18874368,150994944,1207959552,
%T A168974 9663676416,77309411328,618475290624,4947802324992,39582418599936,
%U A168974 316659348799488,2533274790395904,20266198323167232,162129586585337856
%N A168974 Number of reduced words of length n in Coxeter group on 9 generators S_i with relations (S_i)^2 = (S_i S_j)^23 = I.
%C A168974 The initial terms coincide with those of A003951, although the two sequences are eventually different.
%C A168974 First disagreement at index 23: a(23) = 664082786653543858140, A003951(23) = 664082786653543858176. - Klaus Brockhaus, Apr 19 2011
%C A168974 Computed with MAGMA using commands similar to those used to compute A154638.
%H A168974 <a href="/index/Rec#order_23">Index entries for linear recurrences with constant coefficients</a>, signature (7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, -28).
%F A168974 G.f.: (t^23 + 2*t^22 + 2*t^21 + 2*t^20 + 2*t^19 + 2*t^18 + 2*t^17 + 2*t^16 + 2*t^15 + 2*t^14 + 2*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)/(28*t^23 - 7*t^22 - 7*t^21 - 7*t^20 - 7*t^19 - 7*t^18 - 7*t^17 - 7*t^16 - 7*t^15 - 7*t^14 - 7*t^13 - 7*t^12 - 7*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).
%t A168974 With[{num=Total[2t^Range[22]]+t^23+1,den=Total[-7 t^Range[22]]+ 28t^23+ 1},CoefficientList[Series[num/den,{t,0,30}],t]] (* _Harvey P. Dale_, Mar 05 2013 *)
%Y A168974 Cf. A003951 (G.f.: (1+x)/(1-8*x)).
%K A168974 nonn
%O A168974 0,2
%A A168974 _John Cannon_ and _N. J. A. Sloane_, Dec 03 2009