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).




get "libhdr"
manifest $( limit = 100 $)
 
let start() be
$(  let flags = vec limit
    for i = 0 to limit do flags!i := false
 
    for a = 0 to limit by 6
        for b = a to limit by 9
            for c = b to limit by 20
                do flags!c := true
 
    for i = limit to 0 by -1
        unless flags!i
        $(  writef("Maximum non-McNuggets number: %N.*N", i)
            finish
        $)
$)