>This leads to the total of

>2ž2(n - 1) + 1 = 4n - 3,

>which is less than your estimate.

I don't agree with you.
In your case you need one more extra call. And the more groups you divide you'll need more extra calls.

2n-2 is less than 4n-3 or 8n-5.

Am I right??

-Liliya