The pattern described in the initial link is "915". That means throwing a ball to the height of a 9 ball pattern (the height you would throw if juggling 9 ball

The pattern described in the initial link is "915". That means throwing a ball to the height of a 9 ball pattern (the height you would throw if juggling 9 balls normally), next ball to a 1 ball height (essentially handing it across), then the third throw is to a 5 ball pattern height. Then you repeat -- starting with the other hand. The three heights add up to 15, with 3 throws in the sequence, so this is a pattern to be juggled with 5 balls. A three ball sequence would be written as "3". "333" would be the same thing as it is just a repetition of the same "3" sequence. Even numbers are thrown to the same hand. There are more advanced notations for throwing two at the same time, or for a pause, and I'm not sure what a "2" would represent (hold in same hand one beat maybe).