6 coloured squares are placed beside each other as shown below. The leftmost square has the number 504 on it and the right most square has number 2017 on it. A number is to be written on each of the four blank squares so that each number after the second number equals the sum of the previous numbers. Using algebra as a problem solving strategy, determine the remaining four numbers that should be written on the front of the boxes as you move from left to right.