Odd Man Out and Series - General Aptitude

Q1:

1, 2, 6, 15, 31, 56, 91

A 31

B 91

C 56

D 15

ANS:B - 91

1, 1 + 12 = 2, 2 + 22 = 6, 6 + 32 = 15, 15 + 42 = 31, 31 + 52 = 56, 56 + 62 = 92 Last number of given series must be 92 not 91.