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 A166004 #16 Sep 08 2022 08:45:48
%S A166004 1,29,812,22736,636608,17825024,499100672,13974818816,391294926848,
%T A166004 10956257951744,306775222648426,8589706234144560,240511774555729782,
%U A166004 6734329687551532752,188561231251193685024,5279714475026444683776
%N A166004 Number of reduced words of length n in Coxeter group on 29 generators S_i with relations (S_i)^2 = (S_i S_j)^10 = I.
%C A166004 The initial terms coincide with those of A170748, although the two sequences are eventually different.
%C A166004 Computed with MAGMA using commands similar to those used to compute A154638.
%H A166004 G. C. Greubel, <a href="/A166004/b166004.txt">Table of n, a(n) for n = 0..500</a>
%H A166004 <a href="/index/Rec#order_10">Index entries for linear recurrences with constant coefficients</a>, signature (27,27,27,27,27,27,27,27,27,-378).
%F A166004 G.f.: (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)/(378*t^10 - 27*t^9 - 27*t^8 - 27*t^7 - 27*t^6 - 27*t^5 - 27*t^4 - 27*t^3 - 27*t^2 - 27*t + 1).
%p A166004 seq(coeff(series((1+t)*(1-t^10)/(1-28*t+405*t^10-378*t^11), t, n+1), t, n), n = 0..30); # _G. C. Greubel_, Oct 25 2019
%t A166004 CoefficientList[Series[(1+t)*(1-t^10)/(1-28*t+405*t^10-378*t^11), {t, 0, 30}], t] (* _G. C. Greubel_, Apr 21 2016 *)
%t A166004 coxG[{10, 378, -27}] (* The coxG program is at A169452 *) (* _G. C. Greubel_, Oct 25 2019 *)
%o A166004 (PARI) my(t='t+O('t^30)); Vec((1+t)*(1-t^10)/(1-28*t+405*t^10-378*t^11)) \\ _G. C. Greubel_, Oct 25 2019
%o A166004 (Magma) R<t>:=PowerSeriesRing(Integers(), 30); Coefficients(R!( (1+t)*(1-t^10)/(1-28*t+405*t^10-378*t^11) )); // _G. C. Greubel_, Oct 25 2019
%o A166004 (Sage)
%o A166004 def A166004_list(prec):
%o A166004 P.<t> = PowerSeriesRing(ZZ, prec)
%o A166004 return P((1+t)*(1-t^10)/(1-28*t+405*t^10-378*t^11)).list()
%o A166004 A166004_list(30) # _G. C. Greubel_, Oct 25 2019
%o A166004 (GAP) a:=[29, 812, 22736, 636608, 17825024, 499100672, 13974818816, 391294926848, 10956257951744, 306775222648426];; for n in [11..30] do a[n]:=27*Sum([1..9], j-> a[n-j]) - 378*a[n-10]; od; Concatenation([1], a); # _G. C. Greubel_, Oct 25 2019
%K A166004 nonn
%O A166004 0,2
%A A166004 _John Cannon_ and _N. J. A. Sloane_, Dec 03 2009