1 1 8 16 -- --

$$\frac{1}{8} - \frac{1}{16} = \frac{1 \cdot 2}{8 \cdot 2} - \frac{1}{16} = \frac{2}{16} - \frac{1}{16} = \frac{1}{16}$$

Ответ: $$\frac{1}{16}$$