Wikipedia
The McNuggets version of the coin problem was introduced by Henri Picciotto,
who included it in his algebra textbook co-authored with Anita Wah. Picciotto
thought of the application in the 1980s while dining with his son at
McDonald's, working the problem out on a napkin. A McNugget number is
the total number of McDonald's Chicken McNuggets in any number of boxes.
In the United Kingdom, the original boxes (prior to the introduction of
the Happy Meal-sized nugget boxes) were of 6, 9, and 20 nuggets.

Task

Calculate (from 0 up to a limit of 100) the largest non-McNuggets
number (a number n which cannot be expressed with 6x + 9y + 20z = n
where x, y and z are natural numbers).




10 DEFINT A-Z: DIM F(100)
20 FOR A=0 TO 100 STEP 6
30 FOR B=A TO 100 STEP 9
40 FOR C=B TO 100 STEP 20
50 F(C)=-1
60 NEXT C,B,A
70 FOR A=100 TO 0 STEP -1
80 IF NOT F(A) THEN PRINT A: END
90 NEXT A