Find a recurrence relation for the number of strictly increasing sequences of positive integers that have 1 as their first term and n as their last term, where n is a positive integer. that is, sequences a1 , a2 , ak , where a1 = 1, ak = n, and aⱼ < aⱼ ₊ ₁ for j = 1, 2, . . , k − 1.