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#4b344c30-462c-4cc1-b85a-fe0195f2c129中等解答题数列求和方法数列

5. 已知数列{an}\{a_{n}\}为等比数列,在数列{bn}\{b_{n}\}中,b1=2b_{1}=2b2=4b_{2}=4,且an+1=an(bn+1bn)a_{n+1}=a_{n}(b_{n+1}-b_{n})
(1)求数列{bn}\{b_{n}\}的通项公式;
(2)若a1=1a_{1}=1cn=an+bnc_{n}=a_{n}+b_{n},求数列{cn}\{c_{n}\}的前nn项和SnS_{n}