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#13408912-9df6-4728-9293-cfe8746fe73f中等解答题数列求和方法数列

4. 等差数列{an}\{a_{n}\}的前nn项和为SnS_{n},满足a2=5a_{2}=5S5=35S_{5}=35. (1)求{an}\{a_{n}\}的通项公式; (2)设bn=2an(nN){b}_{n}={2}^{{a}_{n}}(n\in {N}^{*}),求证数列{bn}\{b_{n}\}为等比数列,并求其前nn项和TnT_{n}