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#e2d08fd4-0424-41fa-a8e5-71e67f4d77c6简单填空题数列求和方法数列

4.已知数列{an}\{a_{n}\}满足1an=1+2+4++2n1\frac{1}{a_n}=1+2+4+\ldots +{2^{n-1}},数列{(λn+1)(2n1)an}\{(\lambda n+1)(2^{n}-1)a_{n}\}的前nn项和为SnS_{n},若SnS_{n}的最大值仅为S8S_{8},则实数λ\lambda的取值范围是((  ))