cp's OEIS Frontend

A170606 Number of reduced words of length n in Coxeter group on 21 generators S_i with relations (S_i)^2 = (S_i S_j)^48 = I.

%I A170606 #6 Nov 21 2016 12:09:28
%S A170606 1,21,420,8400,168000,3360000,67200000,1344000000,26880000000,
%T A170606 537600000000,10752000000000,215040000000000,4300800000000000,
%U A170606 86016000000000000,1720320000000000000,34406400000000000000
%N A170606 Number of reduced words of length n in Coxeter group on 21 generators S_i with relations (S_i)^2 = (S_i S_j)^48 = I.
%C A170606 The initial terms coincide with those of A170740, although the two sequences are eventually different.
%C A170606 Computed with MAGMA using commands similar to those used to compute A154638.
%H A170606 <a href="/index/Rec#order_48">Index entries for linear recurrences with constant coefficients</a>, signature (19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, -190).
%F A170606 G.f. (t^48 + 2*t^47 + 2*t^46 + 2*t^45 + 2*t^44 + 2*t^43 + 2*t^42 + 2*t^41 +
%F A170606 2*t^40 + 2*t^39 + 2*t^38 + 2*t^37 + 2*t^36 + 2*t^35 + 2*t^34 + 2*t^33 +
%F A170606 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 A170606 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 A170606 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 A170606 2*t^8 + 2*t^7 + 2*t^6 + 2*t^5 + 2*t^4 + 2*t^3 + 2*t^2 + 2*t +
%F A170606 1)/(190*t^48 - 19*t^47 - 19*t^46 - 19*t^45 - 19*t^44 - 19*t^43 - 19*t^42
%F A170606 - 19*t^41 - 19*t^40 - 19*t^39 - 19*t^38 - 19*t^37 - 19*t^36 - 19*t^35 -
%F A170606 19*t^34 - 19*t^33 - 19*t^32 - 19*t^31 - 19*t^30 - 19*t^29 - 19*t^28 -
%F A170606 19*t^27 - 19*t^26 - 19*t^25 - 19*t^24 - 19*t^23 - 19*t^22 - 19*t^21 -
%F A170606 19*t^20 - 19*t^19 - 19*t^18 - 19*t^17 - 19*t^16 - 19*t^15 - 19*t^14 -
%F A170606 19*t^13 - 19*t^12 - 19*t^11 - 19*t^10 - 19*t^9 - 19*t^8 - 19*t^7 -
%F A170606 19*t^6 - 19*t^5 - 19*t^4 - 19*t^3 - 19*t^2 - 19*t + 1)
%K A170606 nonn
%O A170606 0,2
%A A170606 _John Cannon_ and _N. J. A. Sloane_, Dec 03 2009