数列求和是数列的重要内容,同时数列求和的过程中也蕴涵着丰富的数学思想方法,所以亦是高考的考查热点.等差、等比数列的前n项和,主要是应用公式求解.而有些数列,乍看既不是等差数列也不是等比数列,求这些数列的和就不能直接套用公式,而应当根据它们的各自特点来寻找恰当的解题方法. Sequence summation is an important part of the sequence, and the process of summation of sequences implies a wealth of mathematical thinking methods, so it is also a hot spot for examination of college entrance examination. While some series, at first glance, are neither arithmetic nor arithmetic equivalents, the sum of these series can not be directly applied to the formula, but rather should be based on their respective characteristics to find the appropriate solution.