The second number in the given number pairs is obtained by performing certain mathematical operation(s) on the first number. The same operation(s) are followed in all the number pairs except one. Find that odd number pair.

18 : 1620

The logic followed here is :

(Ist number × 2)²  = second number

(16 × 2)²  = (32)² = 1024

(14 × 2)²  = (28)² = 784

(18 × 2)²  = (36)² =1296 ≠ 1620

(12 × 2)²  = (24)² = 576