This is like a "doubling cube", but instead of the numbers doubling for each face, they go up as Fibonacci numbers (and it's an octahedron instead of a cube). Since the ratio of successive terms of the Fibonacci sequence approaches a constant (the Golden Ratio) it's still going up more or less geometrically, but with a smaller jump than doubling. The limit is approached pretty slowly, but you can see it even in the eight numbers supplied here, getting close to 1.618.... A normal doubling cube goes from 2 to 64, but with the slower growth of the Fibonacci sequence a cube could only get us from 2 to 21, so this has two more sides, giving us: 2, 3, 5, 8, 13, 21, 34, 55. So at least it's in the same neighborhood.