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使不等式1/n(n+1)+1/(n+1)(n+2)+...+1/(2n-1)2n
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数学不等式证明题n=1,2,……证明:(1/n)^n+(1/2)^n+……+(n/n)^n第二个是(2/n)^n
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n(n+1)(n+2)数列求和
n(n+1)(n+2)等于多少?