Find the rule and fill in the number: 1,5 / 2,25 / 4, (), ()

Find the rule and fill in the number: 1,5 / 2,25 / 4, (), ()

This is an equal ratio sequence. The first term is multiplied by 5 / 2 to get the last term
2 / 5 × 5 / 2 = 1
1 × 5 / 2 = 5 / 2
5 / 2 × 5 / 2 = 25 / 4
25 / 4 × 5 / 2 = 125 / 8
125 / 8 × 5 / 2 = 625 / 16