You start with 0 and then proceed as follows:
1, 8, 2, 1, 11, 9, 18, ??, 90
There's no other number after 90 in this sequence. In fact, it's impossible to find!
One of the numbers can be replaced by another number, but this sequence would take up alot more space if so, so I made an exception and made it simpler.
So, what is the rule of this sequence? What number is the exception(why)? And what two-digit number is missing?
EDIT: Made a mistake in the sequence! It's correct now. Guess, it will be easier now...