We have n chips numbered 1, 2,…, n. Tom, who likes fancy experiments, selects a chip at random and if the number on that chip is i, he tosses a coin i times

(1 ≤ i ≤ n). Tom has just completed this experiment and he tells us that no heads appeared in the coin tossing. What is the probability that the number of coin tosses was k (for k = 1, 2,…, n)?