数列的通项公式是数列第n项与序号n之间的关系式.利用递推,可得出一系列关系,即数列的第n项与项数n的关系,这就是数列通项公式的本质特征,即递推性,这个特性常常用来解决数列的一些基本问题,是解决数列问题的重要手段.它对解决数列的周期、an与Sn关系、数列的运算等有着很高的价值. The general formula for a series is the relation between the n-th series and the serial number n.Using recursion, a series of relations can be drawn, that is, the relationship between the n-th term and the number n of the series, which is the This characteristic is often used to solve some basic problems of series and is an important method to solve the series of problems.It is of great value in solving the cycle of series, the relationship between an and Sn, the operation of series, and so on.