A169350 - OEIS

%I #10 May 10 2018 00:15:17

%S 1,49,2352,112896,5419008,260112384,12485394432,599298932736,

%T 28766348771328,1380784741023744,66277667569139712,

%U 3181328043318706176,152703746079297896448,7329779811806299029504,351829430966702353416192

%N Number of reduced words of length n in Coxeter group on 49 generators S_i with relations (S_i)^2 = (S_i S_j)^30 = I.

%C The initial terms coincide with those of A170768, although the two sequences are eventually different.

%C First disagreement at index 30: a(30) = 279377845548725526048520704063626166895990498392936, A170768(30) = 279377845548725526048520704063626166895990498394112. - _Klaus Brockhaus_, Jun 23 2011

%C Computed with Magma using commands similar to those used to compute A154638.

%H <a href="/index/Rec#order_30">Index entries for linear recurrences with constant coefficients</a>, signature (47, 47, 47, 47, 47, 47, 47, 47, 47, 47, 47, 47, 47, 47, 47, 47, 47, 47, 47, 47, 47, 47, 47, 47, 47, 47, 47, 47, 47, -1128).

%F G.f.: (t^30 + 2*t^29 + 2*t^28 + 2*t^27 + 2*t^26 + 2*t^25 + 2*t^24 + 2*t^23 + 2*t^22 + 2*t^21 + 2*t^20 + 2*t^19 + 2*t^18 + 2*t^17 + 2*t^16 + 2*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)/(1128*t^30 - 47*t^29 - 47*t^28 - 47*t^27 - 47*t^26 - 47*t^25 - 47*t^24 - 47*t^23 - 47*t^22 - 47*t^21 - 47*t^20 - 47*t^19 - 47*t^18 - 47*t^17 - 47*t^16 - 47*t^15 - 47*t^14 - 47*t^13 - 47*t^12 - 47*t^11 - 47*t^10 - 47*t^9 - 47*t^8 - 47*t^7 - 47*t^6 - 47*t^5 - 47*t^4 - 47*t^3 - 47*t^2 - 47*t + 1).

%Y Cf. A170768 (G.f.: (1+x)/(1-48*x)).

%K nonn

%O 0,2

%A _John Cannon_ and _N. J. A. Sloane_, Dec 03 2009