@Frederick ********
That is NOT "visa-on-arrival" (I believe max 15 days), it is "visa exempt" (60 days, possible to extend once by 30 days).
You (and/or your friend) should look for solid information on the relevant embassy web pages. Unfortunately the Stockholm embassy is not great on providing reliable information (and sometimes are hard to deal with by phone/email).
I believe the Washington embassy to have much better web pages about this.
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