Okular PDF page number confusion

Okular’s page numbering confuses me – help!

Here’s a PDF with ~700 pages. Numbering starts with 1 on “physical” page 3. The screenshot below reflects that:

“Physical” page 102, logical page 100. The 102 appears twice at the top of the screen.

However, when I scroll on to the next page, suddenly I get three different page numbers:

“Physical” page 103 of 599, this makes sense.

The logical number that is printed on the bottom of the page says 101, this also makes sense.

But why does Okular suddenly say “105” rather than “103” at the top? Now I am looking at three page numbers, 101, 103, and 105. This confuses me. If I want to jump to, say, logical page 327 (so that the page has the number 327 printed at the bottom), what number do I have to enter into the text box at the top of the screen? 327+2 or 327+4 or 327+x? Is it even predictable at all?