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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]​​
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$Failed
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$Version
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13.2.0 for Linux x86 (64-bit) (December 12, 2022)