1*1*1=1
3*3*3=27
5*5*5=125
7*7*7=343
9*9*9=729
...
3*3*3=27
5*5*5=125
7*7*7=343
9*9*9=729
...
1,27,125,?,729,1331 find missing number.
343
The missing number is 343.