Consider a random sequence of binary digits {0, 1} of length 3 (e.g., a legitimate sequence can be 010). We assume that the three digits are generated independently; the probability of generating digit 1 is 0.4 and the probability of generating digit 0 is 0.6. Let X be the total number of 1's in the sequence and Y be the sum of the first digit and the last digit of the sequence. What is the probability mass function Px.y(x, y)