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 A167937 #22 Sep 11 2023 01:48:56
%S A167937 1,23,506,11132,244904,5387888,118533536,2607737792,57370231424,
%T A167937 1262145091328,27767192009216,610878224202752,13439320932460544,
%U A167937 295665060514131968,6504631331310903296,143101889288839872512
%N A167937 Number of reduced words of length n in Coxeter group on 23 generators S_i with relations (S_i)^2 = (S_i S_j)^16 = I.
%C A167937 The initial terms coincide with those of A170742, although the two sequences are eventually different.
%C A167937 Computed with MAGMA using commands similar to those used to compute A154638.
%H A167937 G. C. Greubel, <a href="/A167937/b167937.txt">Table of n, a(n) for n = 0..500</a>
%H A167937 <a href="/index/Rec#order_16">Index entries for linear recurrences with constant coefficients</a>, signature (21,21,21,21,21,21,21,21,21,21,21,21,21,21,21,-231).
%F A167937 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)/( 231*t^16 - 21*t^15 - 21*t^14 - 21*t^13 - 21*t^12 - 21*t^11 - 21*t^10 - 21*t^9 - 21*t^8 - 21*t^7 - 21*t^6 - 21*t^5 - 21*t^4 - 21*t^3 - 21*t^2 - 21*t + 1).
%F A167937 From _G. C. Greubel_, Sep 10 2023: (Start)
%F A167937 G.f.: (1+t)*(1-t^16)/(1 - 22*t + 252*t^16 - 231*t^17).
%F A167937 a(n) = 21*Sum_{j=1..15} a(n-j) - 231*a(n-16). (End)
%t A167937 CoefficientList[Series[(1+t)*(1-t^16)/(1-22*t+252*t^16-231*t^17), {t, 0, 50}], t] (* _G. C. Greubel_, Jul 01 2016; Sep 10 2023 *)
%t A167937 coxG[{16,231,-21}] (* The coxG program is at A169452 *) (* _Harvey P. Dale_, Dec 27 2016 *)
%o A167937 (Magma) R<x>:=PowerSeriesRing(Integers(), 40); Coefficients(R!( (1+x)*(1-x^16)/(1-22*x+252*x^16-231*x^17) )); // _G. C. Greubel_, Sep 10 2023
%o A167937 (SageMath)
%o A167937 def A167937_list(prec):
%o A167937 P.<x> = PowerSeriesRing(ZZ, prec)
%o A167937 return P( (1+x)*(1-x^16)/(1-22*x+252*x^16-231*x^17) ).list()
%o A167937 A167937_list(40) # _G. C. Greubel_, Sep 10 2023
%Y A167937 Cf. A154638, A169452, A170742.
%Y A167937 Cf. A167881, A167882, A167896 - A167900, A167908, A167914, A167916, A167919, A167922, A167923, A167924, A167926, A167927, A167929, A167931, A167933, A167935, A167938, A167940 - A167947, A167949 - A167962, A167978, A167980, A167988, A167989.
%K A167937 nonn
%O A167937 0,2
%A A167937 _John Cannon_ and _N. J. A. Sloane_, Dec 03 2009