Have the result of a formula loop back to it's input.

Hi,

I'll start by saying what most say when first comming here for help: I'm fairly new to Grasshopper and came to a stall on my definition.

I have a definition that works through a heigth (R) and returns a new step up in that height (N). I need this to loop so that I run the formula again with a new height that is defined by (R+N) and returns a new (N), is (N2).

So basically it goes;

R + N0 (where N0 = 0)  ---> N1

Then loops;

R + N0 + N1 ---> N2

R + N0 + N1 + N2 ---> N3, etc.

How do I manage this withou having a cycle error?

Please find attached GH and Rhino files.

Sightlines.3dm

Sightlines2.gh

The first  blue group is the basic formul.

The red groups would be the first loop (which I'd have to write down over and over again if I can't manage to resolve this issue) just to show what the result I want is.

The green group is a poor effort on roughly how I'd like the flow to go.

Any light?

Thanks to all,

Rodrigo