terms.
We can proceed indefinitely with the process of thinning out the inductive numbers. For example, we can place first the odd numbers, then their doubles, then the doubles of these, and so on. We thus obtain the series
of which the number is
, since it is a progression of progressions. Any one of the progressions in this new series can of course be thinned out as we thinned out our original progression. We can proceed to
,
