3 random numbers

[MrGoat]

So I was given this question : Pick any 3 random ascending numbers and write out a loop function that prints out all 3 numbers. This was the code and solution presented to me. Can anyone understand it and explain it to me please ? I have looked at it but cannot see how it was derived and why the correct solution was printed. Thanks alot !

# any 3 ascending numbers , counter must start at 0. 
# 400 467 851
i = 0
x = 400
while x < 852:
    print(x)
    if i > 0:
        x = x + ((i + 4) * 67) + (i * 49)
    else:
        x = x + 67
    i = i + 1