Oops: Every cube is within one of a multiple of nine, which means every sum of three cubes is within three of a multiple of nine. So numbers of the form 9k+4 o

Oops: Every cube is within one of a multiple of nine, which means every sum of three cubes is within three of a multiple of nine. So numbers of the form 9k+4 or 9k+5 cannot be expressed as the sum of three cubes. It’s conjectured that every other whole number can be. https://twitter.com/robinhouston/status/1169938974246342658?s=19 https://twitter.com/robinhouston/status/1169938974246342658?...