What are the rules of the number arrangement of 0 1 2 6 16 44 120?

What are the rules of the number arrangement of 0 1 2 6 16 44 120?

The first-order sequence: 0, 1, 2, 6, 16, 44, 120, the latter minus the former to get a new sequence, we call it the second-order sequence, and so on. The second-order sequence: 1, 1, 4, 10, 28, 76 three groups of sequence: 0, 3, 6, 18, 48 four-order sequence: 3, 3, 12, 30, and then divide each item by 3 five-order sequence: 1, 1