The smallest odd inlay square is a (not pure) 3x3 magic square inside a (pure) 5x5 magic square. It is possible to use the consecutive middle 9 numbers from 1 up to 25 to construct the inlay. Use the 8 highest numbers and the 8 lowest numbers to construct the border. See the result below:

Number + 8      =       add border       =    3x3 in 5x5 magic square