This reminds me of Microsoft skipping Windows 9 and going from Windows 8 to Windows 10.
Their Xbox went to 360 second, then "One" third then "Series". Like that makes any sense at all.
Then the series would spell out X □ ○ ∆ .
This is ignoring the battery charging, alternate modes, etc. Just the main USB versions.
Steve Ballmer wanted a "One Microsoft", SkyDrive being renamed to OneDrive was partly due to this, and was hoping people would call the XBox One "The One".