[seqfan] A171942 = A057168(n) - n?

[Marc LeBrun]

Inspired by Peter's "bit fiddlers" thread I calculated A057168(n) - n (the
difference between n and the next number with the same binary weight) and it
matches A171942 "Forwards Van Eck transform of A000120" (the weight of n).

Not understanding this Van Eck transform I wonder if anyone can enlighten
me: is this obvious or, perhaps, a somewhat interesting self-similarity?