1/n级数的发散性证明

S(2^n)=1+1/2+(1/3+1/4)
+(1/5+1/6+1/7+1/8)
+……
+{1/[2^{(n-1)+1]+1/[2}(n-1)+2]+……+1/2^n}
≥1+1/2+1/2+……+1/2
=1+n/2
∴limS(2^n)=+∞
∴∑1/n发散
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