题目

  Most American students go to traditional public schools. There are about 88, 000 public schools all over the US. Some students attend about 3000 independent public schools called charter schools．                  Charter schools are self-governing. Private companies operate some charter schools. They are similar in some ways to traditional public schools. They receive tax money just as other public schools do. Charter schools must prove to local or state governments that their students are learning. These governments provide the schools with the agreement called 已知一列数：1，1，2，3，5，8，13，21，34，55，89，144，233，…，若第n个数比第n+2个数小233，则n=______．