multiple curves division with graph mapper / and other stuff

Hi guys, this is my first post and i am a little stuck.

The final result of my project should be that on a half of elipsoid (180 degrees) i generate this points on which i will later place some 19cm squares. The points get closer and closer to the middle until the squares will touch and create a screen.

1.Now i managed to divide each section with a graph mapper but i would like that on each copy(rotation) of the curve the number of points will increase (as marked in the plan view)

2.

is it possible to replace either the middle values in the list with 19 or to just replace values (segment lenghts) smaller than 19 with 19 ?  i don't really care about the distances outside this middle zone marked in the picture as long as they grow in a gradient.

i have attached my definition, i now it's a bit messy but maybe it can help