A166568 Number of reduced words of length n in Coxeter group on 14 generators S_i with relations (S_i)^2 = (S_i S_j)^12 = I.
1, 14, 182, 2366, 30758, 399854, 5198102, 67575326, 878479238, 11420230094, 148462991222, 1930018885886, 25090245516427, 326173191712368, 4240251492245496, 55123269398992704, 716602502184321480
Offset: 0
Keywords
Links
- G. C. Greubel, Table of n, a(n) for n = 0..500
- Index entries for linear recurrences with constant coefficients, signature (12,12,12,12,12,12,12,12,12,12,12,-78).
Programs
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Magma
R
:=PowerSeriesRing(Integers(), 40); Coefficients(R!( (1+x)*(1-x^12)/(1-13*x+90*x^12-78*x^13) )); // G. C. Greubel, Dec 03 2024 -
Mathematica
coxG[{12,78,-12}] (* The coxG program is at A169452 *) (* Harvey P. Dale, Feb 03 2015 *) CoefficientList[Series[(1+t)*(1-t^12)/(1-13*t+90*t^12-78*t^13), {t,0,50}], t] (* G. C. Greubel, May 17 2016; Dec 03 2024 *)
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SageMath
def A166568_list(prec): P.
= PowerSeriesRing(ZZ, prec) return P( (1+x)*(1-x^12)/(1-13*x+90*x^12-78*x^13) ).list() A166568_list(40) # G. C. Greubel, Dec 03 2024
Formula
G.f.: (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)/(78*t^12 - 12*t^11 - 12*t^10 - 12*t^9 - 12*t^8 - 12*t^7 - 12*t^6 - 12*t^5 - 12*t^4 - 12*t^3 - 12*t^2 - 12*t +1).
From G. C. Greubel, Dec 03 2024: (Start)
a(n) = 12*Sum_{j=1..11} a(n-j) - 78*a(n-12).
G.f.: (1+x)*(1-x^12)/(1 - 13*x + 90*x^12 - 78*x^13). (End)
Comments