cp's OEIS Frontend

A170229 Number of reduced words of length n in Coxeter group on 28 generators S_i with relations (S_i)^2 = (S_i S_j)^40 = I.

%I A170229 #8 Nov 22 2016 15:24:03
%S A170229 1,28,756,20412,551124,14880348,401769396,10847773692,292889889684,
%T A170229 7908027021468,213516729579636,5764951698650172,155653695863554644,
%U A170229 4202649788315975388,113471544284531335476,3063731695682346057852
%N A170229 Number of reduced words of length n in Coxeter group on 28 generators S_i with relations (S_i)^2 = (S_i S_j)^40 = I.
%C A170229 The initial terms coincide with those of A170747, although the two sequences are eventually different.
%C A170229 Computed with MAGMA using commands similar to those used to compute A154638.
%H A170229 <a href="/index/Rec#order_40">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, 26, 26, 26, 26, 26, 26, -351).
%F A170229 G.f. (t^40 + 2*t^39 + 2*t^38 + 2*t^37 + 2*t^36 + 2*t^35 + 2*t^34 + 2*t^33 +
%F A170229 2*t^32 + 2*t^31 + 2*t^30 + 2*t^29 + 2*t^28 + 2*t^27 + 2*t^26 + 2*t^25 +
%F A170229 2*t^24 + 2*t^23 + 2*t^22 + 2*t^21 + 2*t^20 + 2*t^19 + 2*t^18 + 2*t^17 +
%F A170229 2*t^16 + 2*t^15 + 2*t^14 + 2*t^13 + 2*t^12 + 2*t^11 + 2*t^10 + 2*t^9 +
%F A170229 2*t^8 + 2*t^7 + 2*t^6 + 2*t^5 + 2*t^4 + 2*t^3 + 2*t^2 + 2*t +
%F A170229 1)/(351*t^40 - 26*t^39 - 26*t^38 - 26*t^37 - 26*t^36 - 26*t^35 - 26*t^34
%F A170229 - 26*t^33 - 26*t^32 - 26*t^31 - 26*t^30 - 26*t^29 - 26*t^28 - 26*t^27 -
%F A170229 26*t^26 - 26*t^25 - 26*t^24 - 26*t^23 - 26*t^22 - 26*t^21 - 26*t^20 -
%F A170229 26*t^19 - 26*t^18 - 26*t^17 - 26*t^16 - 26*t^15 - 26*t^14 - 26*t^13 -
%F A170229 26*t^12 - 26*t^11 - 26*t^10 - 26*t^9 - 26*t^8 - 26*t^7 - 26*t^6 - 26*t^5
%F A170229 - 26*t^4 - 26*t^3 - 26*t^2 - 26*t + 1)
%t A170229 coxG[{40,351,-26}] (* The coxG program is at A169452 *) (* _Harvey P. Dale_, Aug 27 2014 *)
%K A170229 nonn
%O A170229 0,2
%A A170229 _John Cannon_ and _N. J. A. Sloane_, Dec 03 2009