I'm afraid I still don't understand what your resulting column should look like.
You've written:
Z(i,j) = x * 5y;
and you've said that you want:
- i to go from 0 to 90
- j to go from 0 to 180
So, do you want your z column filled with:
z(0,0) = 0 * 5 * 0 = 0
...
z(90, 180) = 90 * 5 * 180 = 81000
As @Craige_Hales pointed out, the For() function isn't (generally speaking) appropriate for use in a formula column, nor is it required.
In this case you should use the Count() or Sequence() functions in an i column and a j column to build a data table with your i and j sequences and then a z column with the formula:
i * 5 * j
Edit: Attaching a data table that shows Count() and Sequence() columns.
-Jeff