∑j=anf⁡(j)=∫anf⁡(x)⁢ⅆ⁡x+12⁢f⁡(a)+12⁢f⁡(n)+∑s=1m-1B2⁢s(2⁢s)!⁢(f(2⁢s-1)⁡(n)-f(2⁢s-1)⁡(a))+∫anB2⁢m-B~2⁢m⁡(x)(2⁢m)!⁢f(2⁢m)⁡(x)⁢ⅆ⁡x.