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设正项等比数列{an}的首项a1=,前n项和为Sn,且210S30-(210+1)S20+S10=0,则an=_ .
设正项等比数列{an}的首项a1=,前n项和为Sn,且210S30-(210+1)S20+S10=0,求{an}的通项.
设正项等比数列{an}的首项a1=,前n项和为Sn,且210S30-(210+1)S20+S10=0.
(I)求{an}的通项公式;
(II)求数列{nSn}的前n项和Tn.
设正项等比数列{an}的前n项和为Sn,已知a3=4,a4a5a6=212.
(Ⅰ)求首项a1和公比q的值;
(Ⅱ)若Sn=210-1,求n的值.