The OEIS is supported by the many generous donors to the OEIS Foundation.
%I #9 Nov 23 2016 22:07:55
%S 1,11,110,1100,11000,110000,1100000,11000000,110000000,1099999945,
%T 10999998900,109999983555,1099999781100,10999997266500,
%U 109999967220000,1099999617750000,10999995633000000,109999950885000000
%N Number of reduced words of length n in Coxeter group on 11 generators S_i with relations (S_i)^2 = (S_i S_j)^9 = I.
%C The initial terms coincide with those of A003953, although the two sequences are eventually different.
%C Computed with MAGMA using commands similar to those used to compute A154638.
%H <a href="/index/Rec#order_09">Index entries for linear recurrences with constant coefficients</a>, signature (9, 9, 9, 9, 9, 9, 9, 9, -45).
%F G.f. (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 +
%F 1)/(45*t^9 - 9*t^8 - 9*t^7 - 9*t^6 - 9*t^5 - 9*t^4 - 9*t^3 - 9*t^2 - 9*t
%F + 1)
%t With[{num=Total[2t^Range[8]]+t^9+1,den=Total[-9 t^Range[8]]+45t^9+1}, CoefficientList[Series[num/den,{t,0,30}],t]] (* _Harvey P. Dale_, Oct 22 2011 *)
%K nonn
%O 0,2
%A _John Cannon_ and _N. J. A. Sloane_, Dec 03 2009