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 A167927 #20 Sep 11 2023 01:44:16
%S A167927 1,18,306,5202,88434,1503378,25557426,434476242,7386096114,
%T A167927 125563633938,2134581776946,36287890208082,616894133537394,
%U A167927 10487200270135698,178282404592306866,3030800878069216722,51523614927176684121
%N A167927 Number of reduced words of length n in Coxeter group on 18 generators S_i with relations (S_i)^2 = (S_i S_j)^16 = I.
%C A167927 The initial terms coincide with those of A170737, although the two sequences are eventually different.
%C A167927 Computed with MAGMA using commands similar to those used to compute A154638.
%H A167927 G. C. Greubel, <a href="/A167927/b167927.txt">Table of n, a(n) for n = 0..500</a>
%H A167927 <a href="/index/Rec#order_16">Index entries for linear recurrences with constant coefficients</a>, signature (16,16,16,16,16,16,16,16,16,16,16,16,16,16,16,-136).
%F A167927 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)/( 136*t^16 - 16*t^15 - 16*t^14 - 16*t^13 - 16*t^12 - 16*t^11 - 16*t^10 - 16*t^9 - 16*t^8 - 16*t^7 - 16*t^6 - 16*t^5 - 16*t^4 - 16*t^3 - 16*t^2 - 16*t + 1).
%F A167927 From _G. C. Greubel_, Sep 10 2023: (Start)
%F A167927 G.f.: (1+t)*(1-t^16)/(1 - 17*t + 152*t^16 - 136*t^17).
%F A167927 a(n) = 16*Sum_{j=1..15} a(n-j) - 136*a(n-16). (End)
%t A167927 CoefficientList[Series[(1+t)*(1-t^16)/(1-17*t+152*t^16-136*t^17), {t, 0, 50}], t] (* _G. C. Greubel_, Jul 01 2016; Sep 10 2023 *)
%t A167927 coxG[{16,136,-16}] (* The coxG program is at A169452 *) (* _Harvey P. Dale_, May 15 2022 *)
%o A167927 (Magma) R<x>:=PowerSeriesRing(Integers(), 40); Coefficients(R!( (1+x)*(1-x^16)/(1-17*x+152*x^16-136*x^17) )); // _G. C. Greubel_, Sep 10 2023
%o A167927 (SageMath)
%o A167927 def A167927_list(prec):
%o A167927 P.<x> = PowerSeriesRing(ZZ, prec)
%o A167927 return P( (1+x)*(1-x^16)/(1-17*x+152*x^16-136*x^17) ).list()
%o A167927 A167927_list(40) # _G. C. Greubel_, Sep 10 2023
%Y A167927 Cf. A154638, A169452, A170737.
%Y A167927 Cf. A167881, A167882, A167896 - A167900, A167908, A167914, A167916, A167919, A167922, A167923, A167924, A167926, A167929, A167931, A167933, A167935, A167937, A167938, A167940 - A167947, A167949 - A167962, A167978, A167980, A167988, A167989.
%K A167927 nonn
%O A167927 0,2
%A A167927 _John Cannon_ and _N. J. A. Sloane_, Dec 03 2009