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 A164631 #11 Feb 22 2024 13:33:24
%S A164631 1,19,342,6156,110808,1994544,35901792,646232085,11632174452,
%T A164631 209379084903,3768822534060,67838787717588,1221097856797728,
%U A164631 21979755624219696,395635496869474254,7121437065054388737
%N A164631 Number of reduced words of length n in Coxeter group on 19 generators S_i with relations (S_i)^2 = (S_i S_j)^7 = I.
%C A164631 The initial terms coincide with those of A170738, although the two sequences are eventually different.
%C A164631 Computed with MAGMA using commands similar to those used to compute A154638.
%H A164631 <a href="/index/Rec#order_07">Index entries for linear recurrences with constant coefficients</a>, signature (17,17,17,17,17,17,-153).
%F A164631 G.f.: (t^7 + 2*t^6 + 2*t^5 + 2*t^4 + 2*t^3 + 2*t^2 + 2*t + 1)/(153*t^7 - 17*t^6 - 17*t^5 - 17*t^4 - 17*t^3 - 17*t^2 - 17*t + 1).
%t A164631 coxG[{7,153,-17}] (* The coxG program is at A169452 *) (* _Harvey P. Dale_, Aug 27 2017 *)
%K A164631 nonn
%O A164631 0,2
%A A164631 _John Cannon_ and _N. J. A. Sloane_, Dec 03 2009