Sn=(n^2)/2+n/2,Tn=1/S1+1/S2+...+1/Sn,求Tn

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Sn=(n^2)/2+n/2,Tn=1/S1+1/S2+...+1/Sn,求TnSn=(n^2)/2+n/2,Tn=1/S1+1/S2+...+1/Sn,求TnSn=(n^2)/2+n/2,Tn=1/

Sn=(n^2)/2+n/2,Tn=1/S1+1/S2+...+1/Sn,求Tn
Sn=(n^2)/2+n/2,Tn=1/S1+1/S2+...+1/Sn,求Tn

Sn=(n^2)/2+n/2,Tn=1/S1+1/S2+...+1/Sn,求Tn
1/sn=2/(n^2+n)=2/n(n+1)=2(1/n-1/(n+1))
Tn=1/S1+1/S2+...+1/Sn
=2(1-1/2+1/2-1/3+.+1/n-1/(n+1))
=2n/(n+1)