来源:学生作业帮 编辑:搜狗做题网作业帮 分类:数学作业 时间:2024/08/19 14:15:31
![](http://img.wesiedu.com/upload/6/6f/66f22b3e0e3e6a969e78e5573eaf16ae.jpg)
如何计算,请写出计算过程
求和号不会打我用E带了,求和后函数用空格隔开了
T(n)=EiEjEk 1
=EiEj j
=Ei (1+2+...+i)
=Ei i(i+1)/2
=1*2/2+2*3/2+...+n(n+1)/2
=[1*2+2*3+...+n(n+1)]/2
={1/3[1*2*3-0*1*2+2*3*4-1*2*3+...+(n-1)n(n+1)-(n-2)(n-1)n+n(n+1)(n+2)-(n-1)n(n+1)]}/2
=n(n+1)(n+2)/6