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 A167658 #12 Aug 27 2024 13:47:25
%S A167658 1,9,72,576,4608,36864,294912,2359296,18874368,150994944,1207959552,
%T A167658 9663676416,77309411328,618475290624,4947802324992,39582418599900,
%U A167658 316659348798912,2533274790389028,20266198323094080,162129586584607488
%N A167658 Number of reduced words of length n in Coxeter group on 9 generators S_i with relations (S_i)^2 = (S_i S_j)^15 = I.
%C A167658 The initial terms coincide with those of A003951, although the two sequences are eventually different.
%C A167658 Computed with MAGMA using commands similar to those used to compute A154638.
%H A167658 G. C. Greubel, <a href="/A167658/b167658.txt">Table of n, a(n) for n = 0..500</a>
%H A167658 <a href="/index/Rec#order_15">Index entries for linear recurrences with constant coefficients</a>, signature (7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, -28).
%F A167658 G.f.: (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)/(28*t^15 - 7*t^14 - 7*t^13 - 7*t^12 - 7*t^11 - 7*t^10 - 7*t^9 - 7*t^8 - 7*t^7 - 7*t^6 - 7*t^5 - 7*t^4 - 7*t^3 - 7*t^2 - 7*t + 1).
%t A167658 CoefficientList[Series[(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)/(28*t^15 - 7*t^14 - 7*t^13 - 7*t^12 - 7*t^11 - 7*t^10 - 7*t^9 - 7*t^8 - 7*t^7 - 7*t^6 - 7*t^5 - 7*t^4 - 7*t^3 - 7*t^2 - 7*t + 1), {t, 0, 50}], t] (* _G. C. Greubel_, Jun 18 2016 *)
%t A167658 coxG[{15,28,-7}] (* The coxG program is at A169452 *) (* _Harvey P. Dale_, Aug 27 2024 *)
%K A167658 nonn
%O A167658 0,2
%A A167658 _John Cannon_ and _N. J. A. Sloane_, Dec 03 2009