cp's OEIS Frontend

A170128 Number of reduced words of length n in Coxeter group on 23 generators S_i with relations (S_i)^2 = (S_i S_j)^38 = I.

%I A170128 #8 Feb 05 2019 13:40:31
%S A170128 1,23,506,11132,244904,5387888,118533536,2607737792,57370231424,
%T A170128 1262145091328,27767192009216,610878224202752,13439320932460544,
%U A170128 295665060514131968,6504631331310903296,143101889288839872512
%N A170128 Number of reduced words of length n in Coxeter group on 23 generators S_i with relations (S_i)^2 = (S_i S_j)^38 = I.
%C A170128 The initial terms coincide with those of A170742, although the two sequences are eventually different.
%C A170128 Computed with MAGMA using commands similar to those used to compute A154638.
%H A170128 <a href="/index/Rec#order_38">Index entries for linear recurrences with constant coefficients</a>, signature (21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, -231).
%F A170128 G.f. (t^38 + 2*t^37 + 2*t^36 + 2*t^35 + 2*t^34 + 2*t^33 + 2*t^32 + 2*t^31 +
%F A170128 2*t^30 + 2*t^29 + 2*t^28 + 2*t^27 + 2*t^26 + 2*t^25 + 2*t^24 + 2*t^23 +
%F A170128 2*t^22 + 2*t^21 + 2*t^20 + 2*t^19 + 2*t^18 + 2*t^17 + 2*t^16 + 2*t^15 +
%F A170128 2*t^14 + 2*t^13 + 2*t^12 + 2*t^11 + 2*t^10 + 2*t^9 + 2*t^8 + 2*t^7 +
%F A170128 2*t^6 + 2*t^5 + 2*t^4 + 2*t^3 + 2*t^2 + 2*t + 1)/(231*t^38 - 21*t^37 -
%F A170128 21*t^36 - 21*t^35 - 21*t^34 - 21*t^33 - 21*t^32 - 21*t^31 - 21*t^30 -
%F A170128 21*t^29 - 21*t^28 - 21*t^27 - 21*t^26 - 21*t^25 - 21*t^24 - 21*t^23 -
%F A170128 21*t^22 - 21*t^21 - 21*t^20 - 21*t^19 - 21*t^18 - 21*t^17 - 21*t^16 -
%F A170128 21*t^15 - 21*t^14 - 21*t^13 - 21*t^12 - 21*t^11 - 21*t^10 - 21*t^9 -
%F A170128 21*t^8 - 21*t^7 - 21*t^6 - 21*t^5 - 21*t^4 - 21*t^3 - 21*t^2 - 21*t + 1)
%t A170128 coxG[{38,231,-21}] (* The coxG program is at A169452 *) (* _Harvey P. Dale_, Feb 05 2019 *)
%K A170128 nonn
%O A170128 0,2
%A A170128 _John Cannon_ and _N. J. A. Sloane_, Dec 03 2009