I think something simpler like (n)(n+1)/2 is better. This means that the difference between the n-th and (n+1)-th indentation level is n spaces (barring of by o

I think something simpler like (n)(n+1)/2 is better. This means that the difference between the n-th and (n+1)-th indentation level is n spaces (barring of by one errors I made). We still get a curving indentation, and we are still warned against nesting, but the indentation doesn't explode exponentially.