Proposed a kind of new method to evaluate a class of summation problem.The method first rewrite the single sum as a double sum,then interchange the order of summation,and further obtain the closed form of the sum.Shown the advantages of our method by a few of typical examples.% 针对一类求和问题，提出一种新的方法：先将单和转化为二重和，再交换求和顺序，进而得到和式的封闭形式。通过几个典型实例说明此方法的优势。
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