cp's OEIS Frontend

A169521 Number of reduced words of length n in Coxeter group on 28 generators S_i with relations (S_i)^2 = (S_i S_j)^34 = I.

%I A169521 #6 Nov 26 2016 07:37:26
%S A169521 1,28,756,20412,551124,14880348,401769396,10847773692,292889889684,
%T A169521 7908027021468,213516729579636,5764951698650172,155653695863554644,
%U A169521 4202649788315975388,113471544284531335476,3063731695682346057852
%N A169521 Number of reduced words of length n in Coxeter group on 28 generators S_i with relations (S_i)^2 = (S_i S_j)^34 = I.
%C A169521 The initial terms coincide with those of A170747, although the two sequences are eventually different.
%C A169521 Computed with MAGMA using commands similar to those used to compute A154638.
%H A169521 <a href="/index/Rec#order_34">Index entries for linear recurrences with constant coefficients</a>, signature (26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, -351).
%F A169521 G.f. (t^34 + 2*t^33 + 2*t^32 + 2*t^31 + 2*t^30 + 2*t^29 + 2*t^28 + 2*t^27 +
%F A169521 2*t^26 + 2*t^25 + 2*t^24 + 2*t^23 + 2*t^22 + 2*t^21 + 2*t^20 + 2*t^19 +
%F A169521 2*t^18 + 2*t^17 + 2*t^16 + 2*t^15 + 2*t^14 + 2*t^13 + 2*t^12 + 2*t^11 +
%F A169521 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 +
%F A169521 2*t + 1)/(351*t^34 - 26*t^33 - 26*t^32 - 26*t^31 - 26*t^30 - 26*t^29 -
%F A169521 26*t^28 - 26*t^27 - 26*t^26 - 26*t^25 - 26*t^24 - 26*t^23 - 26*t^22 -
%F A169521 26*t^21 - 26*t^20 - 26*t^19 - 26*t^18 - 26*t^17 - 26*t^16 - 26*t^15 -
%F A169521 26*t^14 - 26*t^13 - 26*t^12 - 26*t^11 - 26*t^10 - 26*t^9 - 26*t^8 -
%F A169521 26*t^7 - 26*t^6 - 26*t^5 - 26*t^4 - 26*t^3 - 26*t^2 - 26*t + 1)
%K A169521 nonn
%O A169521 0,2
%A A169521 _John Cannon_ and _N. J. A. Sloane_, Dec 03 2009