It's hip to be... huh?

We interviewed someone yesterday for a position in our group. I give them a math puzzle, because math skills are important in our group (my own math skills are behind where they need to be, in my opinion). At some point they invariably have part of the answer but haven't seen the full pattern yet.

It's AMAZING how many people, and I mean people with PhDs in math or engineering, don't recognize a pattern from the numbers 1, 4 and 9. :(