Davide's diagram is a double triangle. In each "row", you start at one end with 1, and repeatedly add the corresponding element of the previous row. At the "kink" in the row, you use the center element of the previous row twice, for example 4+2 = 6, 6+2 = 8 in the third row.
The only other wrinkle is that Davide builds the rows of the diagram in alternating directions, so the end you choose to start with alternates between left and right. (I think if you don't alternate ends, you get the powers of three.) At any rate, the resulting sequence seems to be A000834, so I'm not sure what novelty Davide has contributed.
-- Allan