4
E n^2/2
n=0
If I remember correctly, this is how you solve this problem...
0/2 + 1/2 + 4/2 + 9/2 + 16/2 = 15
3
E 1/n^3
n=1
1/1 + 1/8 + 1/27= 251/216
You have it. There are other ways also. For instance, if you had a sum from n=1 to 9054, summing might be onerous. But for small indicies, summing is ok. Normally in ASCII, we write it as
Sigma (n=1,4) n2/2