When the level is 0, it is easy to understand how the numbers with a difference of 1,2,3 and so on come from.

Then we have level 1. Can someone please explain how they are obtained, for example the 6 numbers with a difference of 1 (9,19,23,34,41,45) and the following ones with a difference of 2, so that I can understand the calculation?

I assume that results are produced in the same way for the rest of the levels.

Thank you very much!