Mograph, growth of clone's sizes and distances


I Haven’t been here for a very long time. But now I need some help.
I want to distribute clones of an object along a spline with Mograph. Thereby the objects, as well as the distances should grow in a defined ratio. If the first object has the unit of 1, the last one should have 1.3 units. The distances of the clones should increase accordingly. Each clone’s Ø plus a fixed value. With the Step Effector this is not very logical to realize. The needed size growth is to realize somehow, even if not exactly at the first attempt. But how do I achieve the exact distances at the same time?

C4D R21