tedster - 3:32 am on Feb 26, 2010 (gmt 0)
I suspect Google doesn't actually calculate page N + 1 until you request it
You may be right. They may have created a preliminary data-set, but not filled it out.
This reminds me of some funny stuff I've been noticing -- doing site: operator queries plus a keyword. I'll see "about 180 pages" at the top, but at the bottom there are only two pages to choose from (10 results per page). Somewhere in the process they already knew that there were only 17 results (in this case) that they were going to serve. But the top of the page didn't get the message.