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%I #8 Nov 05 2017 09:37:54
%S 1,42,1722,70602,2894682,118681962,4865960442,199504378122,
%T 8179679503002,335366859622221,13750041244475760,563751691022059680,
%U 23113819331845141200,947666592603219256320,38854330296632296661040
%N Number of reduced words of length n in Coxeter group on 42 generators S_i with relations (S_i)^2 = (S_i S_j)^9 = I.
%C The initial terms coincide with those of A170761, 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 (40, 40, 40, 40, 40, 40, 40, 40, -820).
%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)/(820*t^9 - 40*t^8 - 40*t^7 - 40*t^6 - 40*t^5 - 40*t^4 - 40*t^3 -
%F 40*t^2 - 40*t + 1)
%t coxG[{9,820,-40}] (* The coxG program is at A169452 *) (* _Harvey P. Dale_, Nov 05 2017 *)
%K nonn
%O 0,2
%A _John Cannon_ and _N. J. A. Sloane_, Dec 03 2009
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