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

8 : 66

The logic followed here Is :

(Ist number)² - 1 = second number

4 : 15      = 4² - 1 = 15

12 : 143   = 12² - 1 = 143

8 : 66      = 8² - 1 = 63 ≠ 66

3 : 8        = 3² - 1 = 8