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 A169066 #10 Nov 25 2016 11:53:23
%S A169066 1,5,20,80,320,1280,5120,20480,81920,327680,1310720,5242880,20971520,
%T A169066 83886080,335544320,1342177280,5368709120,21474836480,85899345920,
%U A169066 343597383680,1374389534720,5497558138880,21990232555520,87960930222080
%N A169066 Number of reduced words of length n in Coxeter group on 5 generators S_i with relations (S_i)^2 = (S_i S_j)^25 = I.
%C A169066 The initial terms coincide with those of A003947, although the two sequences are eventually different.
%C A169066 First disagreement at index 25: a(25) = 1407374883553270, A003947(25) = 1407374883553280. - Klaus Brockhaus, Apr 25 2011
%C A169066 Computed with MAGMA using commands similar to those used to compute A154638.
%H A169066 <a href="/index/Rec#order_25">Index entries for linear recurrences with constant coefficients</a>, signature (3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, -6).
%F A169066 G.f.: (t^25 + 2*t^24 + 2*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)/(6*t^25 - 3*t^24 - 3*t^23 - 3*t^22 - 3*t^21 - 3*t^20 - 3*t^19 - 3*t^18 - 3*t^17 - 3*t^16 - 3*t^15 - 3*t^14 - 3*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 A169066 With[{num=Total[2t^Range[24]]+t^25+1,den=Total[-3 t^Range[24]]+ 6t^25+ 1},CoefficientList[Series[num/den,{t,0,30}],t]] (* _Harvey P. Dale_, Dec 18 2012 *)
%Y A169066 Cf. A003947 (G.f.: (1+x)/(1-4*x)).
%K A169066 nonn
%O A169066 0,2
%A A169066 _John Cannon_ and _N. J. A. Sloane_, Dec 03 2009