Find the odd one that does not belong to the group.

(Subtract 4 and add 2 in the first and the second number to get the second and the third number)

First option: 20, 16, 18 → 20 – 4 = 16; 16 + 2 = 18

Second option: 16, 12,14 → 16 – 4 = 12; 12 + 2 = 14

Third option: 14, 11, 13 → 14 – 3 = 11; 11 + 2 = 13

Fourth option:  18, 14, 16 → 18 – 4 = 14; 14 + 2 = 16

Thus, 14, 11, 13 is different as the difference in the first and the second term is 3 instead of 4.