cp's OEIS Frontend

A168856 Number of reduced words of length n in Coxeter group on 35 generators S_i with relations (S_i)^2 = (S_i S_j)^20 = I.

%I A168856 #8 Nov 24 2016 18:38:41
%S A168856 1,35,1190,40460,1375640,46771760,1590239840,54068154560,
%T A168856 1838317255040,62502786671360,2125094746826240,72253221392092160,
%U A168856 2456609527331133440,83524723929258536960,2839840613594790256640,96554580862222868725760
%N A168856 Number of reduced words of length n in Coxeter group on 35 generators S_i with relations (S_i)^2 = (S_i S_j)^20 = I.
%C A168856 The initial terms coincide with those of A170754, although the two sequences are eventually different.
%C A168856 First disagreement at index 20: a(20) = 4386998320617381623051245321645, A170754(20) = 4386998320617381623051245322240. - Klaus Brockhaus, Apr 04 2011
%C A168856 Computed with MAGMA using commands similar to those used to compute A154638.
%H A168856 <a href="/index/Rec#order_20">Index entries for linear recurrences with constant coefficients</a>, signature (33, 33, 33, 33, 33, 33, 33, 33, 33, 33, 33, 33, 33, 33, 33, 33, 33, 33, 33, -561).
%F A168856 G.f.: (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)/(561*t^20 - 33*t^19 - 33*t^18 - 33*t^17 - 33*t^16 - 33*t^15 - 33*t^14 - 33*t^13 - 33*t^12 - 33*t^11 - 33*t^10 - 33*t^9 - 33*t^8 - 33*t^7 - 33*t^6 - 33*t^5 - 33*t^4 - 33*t^3 - 33*t^2 - 33*t + 1).
%Y A168856 Cf. A170754 (G.f.: (1+x)/(1-34*x)).
%K A168856 nonn
%O A168856 0,2
%A A168856 _John Cannon_ and _N. J. A. Sloane_, Dec 03 2009