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 A163187 #10 Mar 23 2020 07:07:08
%S A163187 1,28,756,20412,550746,14859936,400943088,10818033408,291886435386,
%T A163187 7875524871396,212493231821052,5733379591597476,154695004916717538,
%U A163187 4173898512013677720,112617914185202621832,3038596784018807730264
%N A163187 Number of reduced words of length n in Coxeter group on 28 generators S_i with relations (S_i)^2 = (S_i S_j)^4 = I.
%C A163187 The initial terms coincide with those of A170747, although the two sequences are eventually different.
%C A163187 Computed with MAGMA using commands similar to those used to compute A154638.
%H A163187 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (26,26,26,-351).
%F A163187 G.f.: (t^4 + 2*t^3 + 2*t^2 + 2*t + 1)/(351*t^4 - 26*t^3 - 26*t^2 - 26*t + 1).
%t A163187 coxG[{4,351,-26}] (* The coxG program is at A169452 *) (* _Harvey P. Dale_, Jul 05 2017 *)
%o A163187 (PARI) Vec((t^4 + 2*t^3 + 2*t^2 + 2*t + 1)/(351*t^4 - 26*t^3 - 26*t^2 - 26*t + 1) + O(t^20)) \\ _Jinyuan Wang_, Mar 23 2020
%K A163187 nonn
%O A163187 0,2
%A A163187 _John Cannon_ and _N. J. A. Sloane_, Dec 03 2009