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 A168861 #10 Oct 05 2017 19:43:35
%S A168861 1,40,1560,60840,2372760,92537640,3608967960,140749750440,
%T A168861 5489240267160,214080370419240,8349134446350360,325616243407664040,
%U A168861 12699033492898897560,495262306223057004840,19315229942699223188760
%N A168861 Number of reduced words of length n in Coxeter group on 40 generators S_i with relations (S_i)^2 = (S_i S_j)^20 = I.
%C A168861 The initial terms coincide with those of A170759, although the two sequences are eventually different.
%C A168861 First disagreement at index 20: a(20) = 67965344853153279094995775325580, A170759(20) = 67965344853153279094995775326360. - Klaus Brockhaus, Apr 04 2011
%C A168861 Computed with MAGMA using commands similar to those used to compute A154638.
%H A168861 <a href="/index/Rec#order_20">Index entries for linear recurrences with constant coefficients</a>, signature (38, 38, 38, 38, 38, 38, 38, 38, 38, 38, 38, 38, 38, 38, 38, 38, 38, 38, 38, -741).
%F A168861 G.f.: (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)/(741*t^20 - 38*t^19 - 38*t^18 - 38*t^17 - 38*t^16 - 38*t^15 - 38*t^14 - 38*t^13 - 38*t^12 - 38*t^11 - 38*t^10 - 38*t^9 - 38*t^8 - 38*t^7 - 38*t^6 - 38*t^5 - 38*t^4 - 38*t^3 - 38*t^2 - 38*t + 1).
%t A168861 coxG[{20,741,-38}] (* The coxG program is at A169452 *) (* _Harvey P. Dale_, Oct 05 2017 *)
%Y A168861 Cf. A170759 (G.f.: (1+x)/(1-39*x)).
%K A168861 nonn
%O A168861 0,2
%A A168861 _John Cannon_ and _N. J. A. Sloane_, Dec 03 2009