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 A167942 #15 Sep 09 2023 06:53:06
%S A167942 1,27,702,18252,474552,12338352,320797152,8340725952,216858874752,
%T A167942 5638330743552,146596599332352,3811511582641152,99099301148669952,
%U A167942 2576581829865418752,66991127576500887552,1741769316989023076352
%N A167942 Number of reduced words of length n in Coxeter group on 27 generators S_i with relations (S_i)^2 = (S_i S_j)^16 = I.
%C A167942 The initial terms coincide with those of A170746, although the two sequences are eventually different.
%C A167942 Computed with MAGMA using commands similar to those used to compute A154638.
%H A167942 G. C. Greubel, <a href="/A167942/b167942.txt">Table of n, a(n) for n = 0..500</a>
%H A167942 <a href="/index/Rec#order_16">Index entries for linear recurrences with constant coefficients</a>, signature (25,25,25,25,25,25,25,25,25,25,25,25,25,25,25,-325).
%F A167942 G.f.: (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)/( 325*t^16 - 25*t^15 - 25*t^14 - 25*t^13 - 25*t^12 - 25*t^11 - 25*t^10 - 25*t^9 - 25*t^8 - 25*t^7 - 25*t^6 - 25*t^5 - 25*t^4 - 25*t^3 - 25*t^2 - 25*t + 1).
%F A167942 From _G. C. Greubel_, Sep 08 2023: (Start)
%F A167942 G.f.: (1+t)*(1-t^16)/(1 - 26*t + 350*t^16 - 325*t^17).
%F A167942 a(n) = 25*Sum_{j=1..15} a(n-j) - 325*a(n-16). (End)
%t A167942 CoefficientList[Series[(1+t)*(1-t^16)/(1-26*t+350*t^16-325*t^17), {t, 0, 50}], t] (* _G. C. Greubel_, Jul 01 2016; Sep 08 2023 *)
%t A167942 coxG[{16,325,-25}] (* The coxG program is at A169452 *) (* _Harvey P. Dale_, Oct 28 2018 *)
%o A167942 (Magma) R<x>:=PowerSeriesRing(Integers(), 40); Coefficients(R!( (1+x)*(1-x^16)/(1-26*x+350*x^16-325*x^17) )); // _G. C. Greubel_, Sep 08 2023
%o A167942 (SageMath)
%o A167942 def A167942_list(prec):
%o A167942 P.<x> = PowerSeriesRing(ZZ, prec)
%o A167942 return P( (1+x)*(1-x^16)/(1-26*x+350*x^16-325*x^17) ).list()
%o A167942 A167942_list(40) # _G. C. Greubel_, Sep 08 2023
%Y A167942 Cf. A154638, A169452, A170758.
%K A167942 nonn
%O A167942 0,2
%A A167942 _John Cannon_ and _N. J. A. Sloane_, Dec 03 2009