A167952 Number of reduced words of length n in Coxeter group on 36 generators S_i with relations (S_i)^2 = (S_i S_j)^16 = I.
1, 36, 1260, 44100, 1543500, 54022500, 1890787500, 66177562500, 2316214687500, 81067514062500, 2837362992187500, 99307704726562500, 3475769665429687500, 121651938290039062500, 4257817840151367187500, 149023624405297851562500
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 (34,34,34,34,34,34,34,34,34,34,34,34,34,34,34,-595).
Programs
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Magma
R
:=PowerSeriesRing(Integers(), 40); Coefficients(R!( (1+x)*(1-x^16)/(1-35*x+629*x^16-595*x^17) )); // G. C. Greubel, Sep 06 2023 -
Mathematica
coxG[{16,595,-34}] (* The coxG program is at A169452 *) (* Harvey P. Dale, Apr 07 2015 *) CoefficientList[Series[(1+t)*(1-t^16)/(1-35*t+629*t^16-595*t^17), {t, 0, 50}], t] (* G. C. Greubel, Jul 02 2016; Sep 06 2023 *)
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SageMath
def A167955_list(prec): P.
= PowerSeriesRing(ZZ, prec) return P( (1+x)*(1-x^16)/(1-35*x+629*x^16-595*x^17) ).list() A167955_list(40) # G. C. Greubel, Sep 06 2023
Formula
G.f.: (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)/( 595*t^16 - 34*t^15 - 34*t^14 - 34*t^13 - 34*t^12 - 34*t^11 - 34*t^10 - 34*t^9 - 34*t^8 - 34*t^7 - 34*t^6 - 34*t^5 - 34*t^4 - 34*t^3 - 34*t^2 - 34*t + 1).
From G. C. Greubel, Sep 06 2023: (Start)
G.f.: (1+t)*(1-t^16)/(1 - 35*t + 629*t^16 - 595*t^17).
a(n) = 34*Sum_{j=1..15} a(n-j) - 595*a(n-16). (End)
Comments