4th Australian Mathematical Olympiad Problems 1983

A1.  Consider the following sequence: 1/1, 2/1, 1/2, 3/1, 2/2, 1/3, 4/1, 3/2, 2/3, 1/4, 5/1, ... , where we list all m/n with m+n = k in order of decreasing m, and then all m/n with m+n = k+1 etc. Each rational appears many times. Find the first five positions of 1/2. What is the position for the nth occurrence of 1/2? Find an expression for the first occurrence of p/q where p < q and p and