137: McNuggets

McNuggets come in boxes of 3, 6, or 20. You can get 9 by buying a 3-piece and a 6-piece, but you can't get 13.  You can get 21 by buying seven 3-piece boxes, but not 22. You can get 23 with a 20-piece and a 3-piece, etc.

What is the largest number of McNuggets you CAN'T get with some combination of 3-piece, 6-piece or 20-piece boxes?