The sum S of an arithmetic series, starting at a, with difference d, and having n terms is given by first term plus last term times number of terms divided by 2
S=n(a+a+(n-1)d)/2
If this sum is to be zero then we need 0=n(a+a+(n-1)d)/2 or
0=n(a+a+(n-1)d) or, assuming there are n>0 terms
0=2a+(n-1)d. Now you can play.
let a=-5, n=6, and have 0=-10+5d or d=2
-5, -3, -1, 1, 3, 5 sum 0. Create your own examples.