cp's OEIS Frontend

A170661 Number of reduced words of length n in Coxeter group on 28 generators S_i with relations (S_i)^2 = (S_i S_j)^49 = I.

%I A170661 #8 Nov 21 2016 11:26:01
%S A170661 1,28,756,20412,551124,14880348,401769396,10847773692,292889889684,
%T A170661 7908027021468,213516729579636,5764951698650172,155653695863554644,
%U A170661 4202649788315975388,113471544284531335476,3063731695682346057852
%N A170661 Number of reduced words of length n in Coxeter group on 28 generators S_i with relations (S_i)^2 = (S_i S_j)^49 = I.
%C A170661 The initial terms coincide with those of A170747, although the two sequences are eventually different.
%C A170661 Computed with MAGMA using commands similar to those used to compute A154638.
%H A170661 <a href="/index/Rec#order_49">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, 26, 26, 26, 26, 26, 26, 26, 26, 26, -351).
%F A170661 G.f. (t^49 + 2*t^48 + 2*t^47 + 2*t^46 + 2*t^45 + 2*t^44 + 2*t^43 + 2*t^42 +
%F A170661 2*t^41 + 2*t^40 + 2*t^39 + 2*t^38 + 2*t^37 + 2*t^36 + 2*t^35 + 2*t^34 +
%F A170661 2*t^33 + 2*t^32 + 2*t^31 + 2*t^30 + 2*t^29 + 2*t^28 + 2*t^27 + 2*t^26 +
%F A170661 2*t^25 + 2*t^24 + 2*t^23 + 2*t^22 + 2*t^21 + 2*t^20 + 2*t^19 + 2*t^18 +
%F A170661 2*t^17 + 2*t^16 + 2*t^15 + 2*t^14 + 2*t^13 + 2*t^12 + 2*t^11 + 2*t^10 +
%F A170661 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 +
%F A170661 1)/(351*t^49 - 26*t^48 - 26*t^47 - 26*t^46 - 26*t^45 - 26*t^44 - 26*t^43
%F A170661 - 26*t^42 - 26*t^41 - 26*t^40 - 26*t^39 - 26*t^38 - 26*t^37 - 26*t^36 -
%F A170661 26*t^35 - 26*t^34 - 26*t^33 - 26*t^32 - 26*t^31 - 26*t^30 - 26*t^29 -
%F A170661 26*t^28 - 26*t^27 - 26*t^26 - 26*t^25 - 26*t^24 - 26*t^23 - 26*t^22 -
%F A170661 26*t^21 - 26*t^20 - 26*t^19 - 26*t^18 - 26*t^17 - 26*t^16 - 26*t^15 -
%F A170661 26*t^14 - 26*t^13 - 26*t^12 - 26*t^11 - 26*t^10 - 26*t^9 - 26*t^8 -
%F A170661 26*t^7 - 26*t^6 - 26*t^5 - 26*t^4 - 26*t^3 - 26*t^2 - 26*t + 1)
%t A170661 coxG[{49,351,-26}] (* The coxG program is at A169452 *) (* _Harvey P. Dale_, Jul 16 2016 *)
%K A170661 nonn
%O A170661 0,2
%A A170661 _John Cannon_ and _N. J. A. Sloane_, Dec 03 2009