In the series 2, 5, 10, 17, 26, 38, 50, exactly one number is wrong. Find it.

Explanation

1. 01

   The terms are one more than squares: $1^2 + 1, 2^2 + 1, 3^2 + 1, 4^2 + 1, 5^2 + 1$, and the last is $7^2 + 1 = 50$.

2. 02

   The sixth term should be $6^2 + 1 = 37$, so 38 is wrong.