在各项都为正数的等比数列{a n}中，a 1=3，前三项的和等于21，则a 4+a 5+a 6=

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SQL Error: select id,body,options from ***_enewstiku_ where sourceid='13517' and id < 1098024 and id<>'1098024' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku_ where sourceid='13517' and id > 1098024 and id<>'1098024' order by id asc limit 5