设函数<img src="http://jgxm-question.oss-cn-beijing.aliyuncs.com/psst/files/4548602d01444224b31c69133d6dcf79.png?x-oss-process=image/sharpen,200"/>是以<img src="http://jgxm-question.oss-cn-beijing.aliyuncs.com/psst/files/6b59f5ae15c14221a6dfa4442b27cee8.png?x-oss-process=image/sharpen,200"/>为周期的周期函数，其<img src="http://jgxm-question.oss-cn-beijing.aliyuncs.com/psst/files/f2d921d6fe4843a5a52672bc0a07d14e.png?x-oss-process=image/sharpen,200"/>在上的表达式为<img src="http://jgxm-question.oss-cn-beijing.aliyuncs.com/psst/files/af4f56c7a17b4ff0b316222296115db5.png?x-oss-process=image/sharpen,200"/>，则<img src="http://jgxm-question.oss-cn-beijing.aliyuncs.com/psst/files/4548602d01444224b31c69133d6dcf79.png?x-oss-process=image/sharpen,200"/>的傅里叶级数的系数<img src="http://jgxm-question.oss-cn-beijing.aliyuncs.com/psst/files/152cc16309794e3cbc26e526475f5ad6.png?x-oss-process=image/sharpen,200"/>的值为（）.