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.

361 : 332 533 : 504 440 : 411 520 : 481

520 : 481

The logic followed here is : Ist number - 29  = second number 361 - 29 =  332 533 - 29 =  504 440 - 29 =  411 520 - 29 =  491 ≠ 481 (odd)