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 A169409 #14 May 08 2018 00:53:45
%S A169409 1,12,132,1452,15972,175692,1932612,21258732,233846052,2572306572,
%T A169409 28295372292,311249095212,3423740047332,37661140520652,
%U A169409 414272545727172,4556998002998892,50126978032987812,551396758362865932
%N A169409 Number of reduced words of length n in Coxeter group on 12 generators S_i with relations (S_i)^2 = (S_i S_j)^32 = I.
%C A169409 The initial terms coincide with those of A003954, although the two sequences are eventually different.
%C A169409 First disagreement is at index 32, the difference is 66. - _Klaus Brockhaus_, Jun 27 2011
%C A169409 Computed with Magma using commands similar to those used to compute A154638.
%H A169409 <a href="/index/Rec#order_32">Index entries for linear recurrences with constant coefficients</a>, signature (10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, -55).
%F A169409 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)/(55*t^32 - 10*t^31 - 10*t^30 - 10*t^29 - 10*t^28 - 10*t^27 - 10*t^26 - 10*t^25 - 10*t^24 - 10*t^23 - 10*t^22 - 10*t^21 - 10*t^20 - 10*t^19 - 10*t^18 - 10*t^17 - 10*t^16 - 10*t^15 - 10*t^14 - 10*t^13 - 10*t^12 - 10*t^11 - 10*t^10 - 10*t^9 - 10*t^8 - 10*t^7 - 10*t^6 - 10*t^5 - 10*t^4 - 10*t^3 - 10*t^2 - 10*t + 1).
%F A169409 G.f.: (1+2*sum(k=1..31, x^k)+x^32)/(1-10*sum(k=1..31, x^k)+55*x^32).
%t A169409 With[{num=Total[2t^Range[31]]+t^32+1,den=Total[-10 t^Range[31]]+55t^32+ 1},CoefficientList[Series[num/den,{t,0,20}],t]] (* _Harvey P. Dale_, Aug 13 2014 *)
%Y A169409 Cf. A003954 (G.f.: (1+x)/(1-11*x) ).
%K A169409 nonn
%O A169409 0,2
%A A169409 _John Cannon_ and _N. J. A. Sloane_, Dec 03 2009