<img src="http://jgxm-question.oss-cn-beijing.aliyuncs.com/psst/files/2464b799db33442cad0d54727654e963.plain?x-oss-process=image/sharpen,200"/> 在圆环域<img src="http://jgxm-question.oss-cn-beijing.aliyuncs.com/psst/files/01be7f6a554e4726b54f9d414f7143ae.plain?x-oss-process=image/sharpen,200"/> 内的洛朗级数为( )