Which number is wrong in the given series? 2, 9, 26, 50, 82, 121

The series follows the pattern (odd number)² + (incrementing by 1): 1²+1=2, 3²+0=9, 5²+1=26, 7²+1=50 (should be 51 to continue pattern), 9²+1=82 (should be 82 anyway), 11²+0=121. The number 50 breaks the pattern. Between 26 and 50, the increment should have been 2 (5²+2=27), but between 9 and 26 it was 1. Actually, the pattern is more complex: the 'added' term should alternate or increment consistently. 50 is 7²+1, but pattern suggests 7²+2=51.