In[]:=
d=10;R2toSpectrum[R_,d_]:=Module[{h,dd,decay},decay=If[R<1.001,100.,dd/.FindRoot[HarmonicNumber[d,dd]^2/HarmonicNumber[d,2dd]==R,{dd,2,0,100}]];h=Table[i^-decay,{i,1,d}];h/Total[h]];rrPlot2[R_]:=Plot[Max[R2toSpectrum[R,d]],{R,1,d}]rrPlot2[5]
Out[]=
$Failed
In[]:=
$Version
Out[]=
13.2.0 for Linux x86 (64-bit) (December 12, 2022)