How Do I Loft a series of Circles derived from a formula?

Hi all, new here, kinda got to where i want at the moment by reverse engineering a lot of bits and pieces. But this has got me stumped.

As you can hopefully see in the image, i have managed to determine a series of circles which i want to 'Loft' or other to create the shape.

The closest i have gotten is with a Partition List, but that gives me a broken loft, ie not complete.

Thoughts?

Many many thanks