A full procedural and vectorized approach would be as follows:
The cosine and sine are simply the parametric equation of the circle which is periodic, if we scale it based on its parameter, we get the spiral effect, the scale of the objects can be defined as a scalar multiple of the parameter as well.
Select all spheres, Open the python console & type:
a = 0.1 for i in bpy.context.selected_objects: i.scale = (a, a, a) a = a + 0.1
You have to do the math according to you number of objects and the size you want to scale them by to set up the initial value and increase of a.