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 A169438 #16 May 08 2018 01:08:02
%S A169438 1,41,1640,65600,2624000,104960000,4198400000,167936000000,
%T A169438 6717440000000,268697600000000,10747904000000000,429916160000000000,
%U A169438 17196646400000000000,687865856000000000000,27514634240000000000000
%N A169438 Number of reduced words of length n in Coxeter group on 41 generators S_i with relations (S_i)^2 = (S_i S_j)^32 = I.
%C A169438 The initial terms coincide with those of A170760, although the two sequences are eventually different.
%C A169438 First disagreement is at index 32, the difference is 820. - _Klaus Brockhaus_, Jun 30 2011
%C A169438 Computed with Magma using commands similar to those used to compute A154638.
%H A169438 <a href="/index/Rec#order_32">Index entries for linear recurrences with constant coefficients</a>, signature (39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, -780).
%F A169438 G.f.: (t^32 + 2*t^31 + 2*t^30 + 2*t^29 + 2*t^28 + 2*t^27 + 2*t^26 + 2*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)/(780*t^32 - 39*t^31 - 39*t^30 - 39*t^29 - 39*t^28 - 39*t^27 - 39*t^26 - 39*t^25 - 39*t^24 - 39*t^23 - 39*t^22 - 39*t^21 - 39*t^20 - 39*t^19 - 39*t^18 - 39*t^17 - 39*t^16 - 39*t^15 - 39*t^14 - 39*t^13 - 39*t^12 - 39*t^11 - 39*t^10 - 39*t^9 - 39*t^8 - 39*t^7 - 39*t^6 - 39*t^5 - 39*t^4 - 39*t^3 - 39*t^2 - 39*t + 1).
%F A169438 G.f.: (1+2*sum(k=1..31,x^k)+x^32)/(1-39*sum(k=1..31,x^k)+780*x^32).
%t A169438 With[{num=Total[2t^Range[31]]+t^32+1,den=Total[-39 t^Range[31]]+789t^32+ 1},CoefficientList[Series[num/den,{t,0,20}],t]] (* _Harvey P. Dale_, Feb 03 2014 *)
%Y A169438 Cf. A170760 (G.f.: (1+x)/(1-40*x) ).
%K A169438 nonn
%O A169438 0,2
%A A169438 _John Cannon_ and _N. J. A. Sloane_, Dec 03 2009