cp's OEIS Frontend

A169364 Number of reduced words of length n in Coxeter group on 15 generators S_i with relations (S_i)^2 = (S_i S_j)^31 = I.

%I A169364 #10 May 08 2018 00:28:32
%S A169364 1,15,210,2940,41160,576240,8067360,112943040,1581202560,22136835840,
%T A169364 309915701760,4338819824640,60743477544960,850408685629440,
%U A169364 11905721598812160,166680102383370240,2333521433367183360
%N A169364 Number of reduced words of length n in Coxeter group on 15 generators S_i with relations (S_i)^2 = (S_i S_j)^31 = I.
%C A169364 The initial terms coincide with those of A170734, although the two sequences are eventually different.
%C A169364 First disagreement at index 31: a(31) = 363021485332268931329115558657392535, A170734(31) = 363021485332268931329115558657392640. - _Klaus Brockhaus_, Jun 17 2011
%C A169364 Computed with Magma using commands similar to those used to compute A154638.
%H A169364 <a href="/index/Rec#order_31">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, -91).
%F A169364 G.f.: (t^31 + 2*t^30 + 2*t^29 + 2*t^28 + 2*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)/(91*t^31 - 13*t^30 - 13*t^29 - 13*t^28 - 13*t^27 - 13*t^26 - 13*t^25 - 13*t^24 - 13*t^23 - 13*t^22 - 13*t^21 - 13*t^20 - 13*t^19 - 13*t^18 - 13*t^17 - 13*t^16 - 13*t^15 - 13*t^14 - 13*t^13 - 13*t^12 - 13*t^11 - 13*t^10 - 13*t^9 - 13*t^8 - 13*t^7 - 13*t^6 - 13*t^5 - 13*t^4 - 13*t^3 - 13*t^2 - 13*t + 1).
%Y A169364 Cf. A170734 (G.f.: (1+x)/(1-14*x)).
%K A169364 nonn
%O A169364 0,2
%A A169364 _John Cannon_ and _N. J. A. Sloane_, Dec 03 2009