The solution is incorrect. If P(probability of existence of loop of length L) = 1/L, then P(1) = 1, which can be proven false by the existence of arrangements w

The solution is incorrect. If P(probability of existence of loop of length L) = 1/L, then P(1) = 1, which can be proven false by the existence of arrangements without loops of length 1. e.g for N=4: 4,3,2,1 He's making at least one false conclusion around 8:30.