Pick an odd man in the given number series? 4 12 38 87 198

The given series follows a pattern that,

$4 + 32 = 4 + 9 = 1313 + 52 = 13 + 25 = 3838 + 72 = 38 + 49 = 8787 + 92 = 87 + 81 = 198$ 

Hence, the odd man in the given number series is 12.