Bruh, why the hell it's 6 kyu? It's literally 8

Instructions insufficient. How one is supposed to continue a sequence knowing only the first terms ?
That's mathematically undefined.

Instructions not clear.

The test case assumes that the sum of two UINT_MAX has a 33 long representation in binary. While its representation is 1111 1111 1111 1110 (only 32 digits).
So I cannot pass the test.

Closing the issue as invalid.

Ohhhhh ! Now I understand, I iterated on class_size-- so at the end it would be -1.
Thanks for helping me understand my mistake.

did you put it at the top of your solution, as a very first line in your function? can you show your function together with the printf?1

I used a print statement like so

printf("%d\n", class_size)

and it returned -1.

No it does not. Why would you think so?

If race is factual, then what is the definition?

Race is "factual". How could you possibly make scientific studies on biological differences in races if it's illegal to have such databases?

I am not 100% sure: am I allowed to use PL/pgSQL?

The error messages are really not helpful in this kata.