Aptitude Hack#50(14-3-19)

Question:
Which number does not belong in the series below? 
2, 5, 10, 17, 26, 37, 50, 64
A) 17
B) 37
C) 64
D) 26

Answer D) 64

 Explanation: 
Given series is 2,5,10,17,26,37,50,64.

Here the total number of terms are 8..i.e. A(1) to A(8).

For the 1st 7 terms, you can observe the relationship  between the terms which is 
A(n) = [ A(n-1) - {A(n-1) + A(n-2)} + 2 ] 
where n >= 3

Now for the 8th term i.e. A(8), this relationship violates.
According to the relationship,
A(8) = [A(7) + {A(7) - A(6)} + 2 ]
= [50 + {50 - 37} + 2 ]
= 50 + 13 + 2
= 65.
But in the series, it is 64. 
Hence 64 doesn't belong to the series.