Find the odd man out of the following number sequence? 100, 101, 97, 105, 90

The given number series 100, 101, 97, 105, 90

100

100 + 1^2 = 101

101 - 2^2 = 97

97 + 3^2 = 106 ( not 105)

106 - 4^2 = 90

Hence, the odd man in the given series is 105.