在等差数列{a n}中，若a 3+a 9+a 15+a 17＝0，则a 11的值是

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SQL Error: select id,body,options from ***_enewstiku_ where sourceid='13509' and id < 1097193 and id<>'1097193' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku_ where sourceid='13509' and id > 1097193 and id<>'1097193' order by id asc limit 5