HOW TO REPORT is.giuga n:
    \ each prime factor must appear only once, e.g.: for 2:
    \ [ ( n / 2 ) - 1 ] mod 2 = 0  => n / 2 is odd => n isn't divisible by 4
    \ similarly for other primes
    PUT  1, 3, 1, floor( n / 2 ) IN f.count, f, giuga, v
    WHILE f <= v AND giuga = 1:
        IF v mod f = 0:
            PUT f.count + 1 IN f.count
            IF ( ( floor( n / f ) ) - 1 ) mod f <> 0: PUT 0 IN giuga
            PUT floor( v / f ) IN v
        PUT f + 2 IN f
    IF giuga = 1:             \ n is still a candidate, check it is not prime
        IF f.count = 1: FAIL       \ only 1 factor - it is prime so not giuga
    REPORT giuga = 1

PUT 0, -2 IN g.count, n
WHILE g.count < 4:
    PUT n + 4 IN n                          \ assume the numbers are all even
    IF is.giuga n:
        PUT g.count + 1 IN g.count
        WRITE n