%I #10 Jul 13 2018 14:29:19
%S 1,13,156,1872,22464,269568,3234816,38817792,465813504,5589762048,
%T 67077144576,804925734912,9659108818944,115909305827328,
%U 1390911669927936,16690940039135232,200291280469622784
%N Number of reduced words of length n in Coxeter group on 13 generators S_i with relations (S_i)^2 = (S_i S_j)^22 = I.
%C The initial terms coincide with those of A170732, although the two sequences are eventually different.
%C First disagreement at index 22: a(22) = 598066558821806119059378, A170732(22) = 598066558821806119059456 . - Klaus Brockhaus, Apr 09 2011
%C Computed with MAGMA using commands similar to those used to compute A154638.
%H <a href="/index/Rec#order_22">Index entries for linear recurrences with constant coefficients</a>, signature (11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, -66).
%F G.f.: (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)/(66*t^22 - 11*t^21 - 11*t^20 - 11*t^19 - 11*t^18 - 11*t^17 - 11*t^16 - 11*t^15 - 11*t^14 - 11*t^13 - 11*t^12 - 11*t^11 - 11*t^10 - 11*t^9 - 11*t^8 - 11*t^7 - 11*t^6 - 11*t^5 - 11*t^4 - 11*t^3 - 11*t^2 - 11*t + 1).
%t coxG[{22,66,-11}] (* The coxG program is at A169452 *) (* _Harvey P. Dale_, Jul 13 2018 *)
%Y Cf. A170732 (G.f.: (1+x)/(1-12*x)).
%K nonn
%O 0,2
%A _John Cannon_ and _N. J. A. Sloane_, Dec 03 2009
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