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#3d5a3558-41f9-4939-923c-341287cc2473中等填空题等比数列的概念与通项数列

11. 已知SnS_{n}是等比数列{an}\{a_{n}\}的前nn项和,且Sn=2n+1+a{S}_{n}={2}^{n+1}+a,则a1a2+a2a3++a10a11=(a_{1}a_{2}+a_{2}a_{3}+\dotsb +a_{10}a_{11}=(  ))