Maybe I'm missing something or maybe the problem statement got corrupted somehow, but I have no idea what the problem is even asking for: "Crack [whatever that means] the following integer sequence." End-of-problem-statement. Even after looking at the solutions (having to hard code the answers to do so), it's unclear what you were looking for. As written, it seems you were asking for a function that was a simple regurgitation of the "given" sequence terms in the test cases.