A131107 Rectangular array read by antidiagonals: k objects are each put into one of n boxes, independently with equal probability. a(n, k) is the expected number of boxes with exactly one object (n, k >= 1). Sequence gives the denominators.

1, 1, 1, 1, 1, 1, 1, 3, 4, 1, 1, 2, 3, 2, 1, 1, 5, 16, 27, 16, 1, 1, 3, 25, 16, 81, 16, 1, 1, 7, 12, 125, 256, 81, 64, 1, 1, 4, 49, 54, 125, 512, 729, 16, 1, 1, 9, 64, 343, 1296, 3125, 4096, 2187, 256, 1, 1, 5, 27, 128, 2401, 1296, 15625, 2048, 729, 256, 1, 1, 11, 100, 729, 4096