17. A cube with edge length $n$ ($n$ is a positive integer) is painted red on its surface, and then it is cut into $n^{3}$ smaller cubes with edge length 1. It is found that the number of smaller cubes with only one face painted red is exactly 12 times the number of smaller cubes with exactly two faces painted red. Then $n$ equals (
26
【Answer】The number of small cubes with only one face painted red is $6(n-2)^{2}$; the number of small cubes with exactly two faces painted red is $\frac{4(n-2) \times 6}{2}=12(n-2)$; so $12(n-2) \times 12=6(n-2)^{2} \Rightarrow n-2=24 \Rightarrow n=26$