cp's OEIS Frontend

A169195 Number of reduced words of length n in Coxeter group on 38 generators S_i with relations (S_i)^2 = (S_i S_j)^27 = I.

%I A169195 #10 May 10 2018 02:11:45
%S A169195 1,38,1406,52022,1924814,71218118,2635070366,97497603542,
%T A169195 3607411331054,133474219248998,4938546112212926,182726206151878262,
%U A169195 6760869627619495694,250152176221921340678,9255630520211089605086
%N A169195 Number of reduced words of length n in Coxeter group on 38 generators S_i with relations (S_i)^2 = (S_i S_j)^27 = I.
%C A169195 The initial terms coincide with those of A170757, although the two sequences are eventually different.
%C A169195 First disagreement at index 27: a(27) = 2254386745438500136384789907126720090448439, A170757(27) = 2254386745438500136384789907126720090449142. - _Klaus Brockhaus_, May 07 2011
%C A169195 Computed with Magma using commands similar to those used to compute A154638.
%H A169195 <a href="/index/Rec#order_27">Index entries for linear recurrences with constant coefficients</a>, signature (36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, -666).
%F A169195 G.f.: (t^27 + 2*t^26 + 2*t^25 + 2*t^24 + 2*t^23 + 2*t^22 + 2*t^21 + 2*t^20 + 2*t^19 + 2*t^18 + 2*t^17 + 2*t^16 + 2*t^15 + 2*t^14 + 2*t^13 + 2*t^12 + 2*t^11 + 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 + 2*t + 1)/(666*t^27 - 36*t^26 - 36*t^25 - 36*t^24 - 36*t^23 - 36*t^22 - 36*t^21 - 36*t^20 - 36*t^19 - 36*t^18 - 36*t^17 - 36*t^16 - 36*t^15 - 36*t^14 - 36*t^13 - 36*t^12 - 36*t^11 - 36*t^10 - 36*t^9 - 36*t^8 - 36*t^7 - 36*t^6 - 36*t^5 - 36*t^4 - 36*t^3 - 36*t^2 - 36*t + 1).
%Y A169195 Cf. A170757 (G.f.: (1+x)/(1-37*x)).
%K A169195 nonn
%O A169195 0,2
%A A169195 _John Cannon_ and _N. J. A. Sloane_, Dec 03 2009