Hint: Imagine the rest of natural numbers, starting with number 1, on the figure: number 2 is on the square right next to the number 1, number 3 is one square above the number 2, number 4 is left next to the number 3 (i.e. one square above the number 1),... number 6 is down next to the number 5 (i.e. left next to the number 1), etc.

Which type of numbers fall on green squares?