cp's OEIS Frontend

A170242 Number of reduced words of length n in Coxeter group on 41 generators S_i with relations (S_i)^2 = (S_i S_j)^40 = I.

%I A170242 #8 Jun 01 2017 12:06:34
%S A170242 1,41,1640,65600,2624000,104960000,4198400000,167936000000,
%T A170242 6717440000000,268697600000000,10747904000000000,429916160000000000,
%U A170242 17196646400000000000,687865856000000000000,27514634240000000000000
%N A170242 Number of reduced words of length n in Coxeter group on 41 generators S_i with relations (S_i)^2 = (S_i S_j)^40 = I.
%C A170242 The initial terms coincide with those of A170760, although the two sequences are eventually different.
%C A170242 Computed with MAGMA using commands similar to those used to compute A154638.
%H A170242 <a href="/index/Rec#order_40">Index entries for linear recurrences with constant coefficients</a>, signature (39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, -780).
%F A170242 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 A170242 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 A170242 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 A170242 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 A170242 2*t^8 + 2*t^7 + 2*t^6 + 2*t^5 + 2*t^4 + 2*t^3 + 2*t^2 + 2*t +
%F A170242 1)/(780*t^40 - 39*t^39 - 39*t^38 - 39*t^37 - 39*t^36 - 39*t^35 - 39*t^34
%F A170242 - 39*t^33 - 39*t^32 - 39*t^31 - 39*t^30 - 39*t^29 - 39*t^28 - 39*t^27 -
%F A170242 39*t^26 - 39*t^25 - 39*t^24 - 39*t^23 - 39*t^22 - 39*t^21 - 39*t^20 -
%F A170242 39*t^19 - 39*t^18 - 39*t^17 - 39*t^16 - 39*t^15 - 39*t^14 - 39*t^13 -
%F A170242 39*t^12 - 39*t^11 - 39*t^10 - 39*t^9 - 39*t^8 - 39*t^7 - 39*t^6 - 39*t^5
%F A170242 - 39*t^4 - 39*t^3 - 39*t^2 - 39*t + 1)
%t A170242 coxG[{40,780,-39}] (* The coxG program is at A169452 *) (* _Harvey P. Dale_, Jun 01 2017 *)
%K A170242 nonn
%O A170242 0,2
%A A170242 _John Cannon_ and _N. J. A. Sloane_, Dec 03 2009