数列是以正整数集为定义域的特殊函数。数列是一列有序的数。数列中的每一个数称为这个数列的项。数列第n项的取值和n的函数关系一般称为数列的通项公式。数列是初等数学研究中的重要内容之一,其中数列的通项公式的求解是分析数列的基础。在中学数学中,重点学习部分简单的数列,包括等差数列和等比数列,通过这些数列的定义及基本性质,很容易得到他们的通项公式。但除此以外,在实际问题中,我们常遇到利用递推关系确定的特殊数列,而此类数列的通项公式就 A sequence is a special function that takes a set of positive integers as a domain. A sequence is an ordered list of numbers. Each number in a series is called an item in this series. The value of the n-th sequence and the function of n are generally called the general formula of the sequence. The sequence is one of the important contents in the elementary mathematics research. The solution of the general formula of the sequence is the basis for analyzing the sequence. In middle school mathematics, we focus on some simple series, including the arithmetic series and the geometric series. Through the definition and basic properties of these series, we can easily get their formulas. However, in addition to this, in practical problems, we often encounter special sequences determined by recursion, and the general formulas for such series are