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 A168741 #17 Nov 24 2016 13:53:46
%S A168741 1,16,240,3600,54000,810000,12150000,182250000,2733750000,41006250000,
%T A168741 615093750000,9226406250000,138396093750000,2075941406250000,
%U A168741 31139121093750000,467086816406250000,7006302246093750000
%N A168741 Number of reduced words of length n in Coxeter group on 16 generators S_i with relations (S_i)^2 = (S_i S_j)^18 = I.
%C A168741 The initial terms coincide with those of A170735, although the two sequences are eventually different.
%C A168741 First disagreement at index 18: a(18) = 1576418005371093749880, A170735(18) = 1576418005371093750000. - _Klaus Brockhaus_, Mar 27 2011
%C A168741 Computed with MAGMA using commands similar to those used to compute A154638.
%H A168741 G. C. Greubel, <a href="/A168741/b168741.txt">Table of n, a(n) for n = 0..500</a>
%H A168741 <a href="/index/Rec#order_18">Index entries for linear recurrences with constant coefficients</a>, signature (14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, -105).
%F A168741 G.f.: (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)/(105*t^18 - 14*t^17 - 14*t^16 - 14*t^15 - 14*t^14 - 14*t^13 - 14*t^12 - 14*t^11 - 14*t^10 - 14*t^9 - 14*t^8 - 14*t^7 - 14*t^6 - 14*t^5 - 14*t^4 - 14*t^3 - 14*t^2 - 14*t + 1).
%t A168741 With[{num=Total[2t^Range[17]]+t^18+1,den=Total[-14 t^Range[17]]+ 105t^18+ 1}, CoefficientList[Series[num/den,{t,0,30}],t]] (* _Harvey P. Dale_, Oct 04 2011 *)
%t A168741 CoefficientList[Series[(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)/(105*t^18 - 14*t^17 - 14*t^16 - 14*t^15 - 14*t^14 - 14*t^13 - 14*t^12 - 14*t^11 - 14*t^10 - 14*t^9 - 14*t^8 - 14*t^7 - 14*t^6 - 14*t^5 - 14*t^4 - 14*t^3 - 14*t^2 - 14*t + 1), {t, 0, 50}], t] (* _G. C. Greubel_, Aug 10 2016 *)
%Y A168741 Cf. A170735 (G.f.: (1+x)/(1-15*x)).
%K A168741 nonn,easy
%O A168741 0,2
%A A168741 _John Cannon_ and _N. J. A. Sloane_, Dec 03 2009