cp's OEIS Frontend

A170216 Number of reduced words of length n in Coxeter group on 15 generators S_i with relations (S_i)^2 = (S_i S_j)^40 = I.

%I A170216 #6 Nov 22 2016 15:17:22
%S A170216 1,15,210,2940,41160,576240,8067360,112943040,1581202560,22136835840,
%T A170216 309915701760,4338819824640,60743477544960,850408685629440,
%U A170216 11905721598812160,166680102383370240,2333521433367183360
%N A170216 Number of reduced words of length n in Coxeter group on 15 generators S_i with relations (S_i)^2 = (S_i S_j)^40 = I.
%C A170216 The initial terms coincide with those of A170734, although the two sequences are eventually different.
%C A170216 Computed with MAGMA using commands similar to those used to compute A154638.
%H A170216 <a href="/index/Rec#order_40">Index entries for linear recurrences with constant coefficients</a>, signature (13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, -91).
%F A170216 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 A170216 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 A170216 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 A170216 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 A170216 2*t^8 + 2*t^7 + 2*t^6 + 2*t^5 + 2*t^4 + 2*t^3 + 2*t^2 + 2*t +
%F A170216 1)/(91*t^40 - 13*t^39 - 13*t^38 - 13*t^37 - 13*t^36 - 13*t^35 - 13*t^34
%F A170216 - 13*t^33 - 13*t^32 - 13*t^31 - 13*t^30 - 13*t^29 - 13*t^28 - 13*t^27 -
%F A170216 13*t^26 - 13*t^25 - 13*t^24 - 13*t^23 - 13*t^22 - 13*t^21 - 13*t^20 -
%F A170216 13*t^19 - 13*t^18 - 13*t^17 - 13*t^16 - 13*t^15 - 13*t^14 - 13*t^13 -
%F A170216 13*t^12 - 13*t^11 - 13*t^10 - 13*t^9 - 13*t^8 - 13*t^7 - 13*t^6 - 13*t^5
%F A170216 - 13*t^4 - 13*t^3 - 13*t^2 - 13*t + 1)
%K A170216 nonn
%O A170216 0,2
%A A170216 _John Cannon_ and _N. J. A. Sloane_, Dec 03 2009