[mamaniscalco]

"Write a function which produces the prime factors of a given integer."

The kinds of people that I'm tasked with interviewing are not web developers nor user interface types but are generally more back end/non off the shelf solutions type of programmers. I also point out that I realize that it's an atypical programming question and I let them think about it on their own for 5-10 minutes if needed before helping them along if they go astray.

How they react to the question is as telling as how long it takes them to realize that they do not need a function to determine if a number is prime or not.