1 + 4 + 9 + 16 + 25 + 36 + 49 + 64=204
3 5 7 9 11 13 15 the difference between the numbers in the lines over
2 2 2 2 2 2 the difference between the numbers in the lines over
I only found out the numbers 1,4 and 9, and on the I used my knowledge about the difference on the numbers.