Hi! I'm not 100% sure I fully understood what you said. The outside digit being X means that the first X number of that direction has the same parity, and the (X+1)th number has a different parity. So, for example, in row 6, when you look from the left, the first digit is 7 (odd), and the second digit is 6 (even), which is of different parity from the first digit. So the outside number should be 1 from that direction, and similarly if you look from the right.