I got a call to come into their office for an interview for a software developer position with the CTO of the company. I was asked when I would like to come in and we scheduled a time. I live in a different city and was surprised they didn't want to do an initial phone interview to get a feel for what I was like and if I was a good "fit".
So for the interview day I basically spent at least three hours getting there. When I got to the interview, there was no one in the lobby so I sat in the lobby at least for five minutes after the interview was scheduled to start. Finally, a woman came out to ask if I had been helped by someone.... I said no. She went into another room and talked to some people, and I heard laughing, what is so funny? So she went and found my interviewer was still in the middle of the meeting, and would be with me shortly.
Finally, the CTO came out, customary greetings, and we went into the interview room. He then asked me about any projects that I had done I am proud of. I mentioned a couple, he asked questions and didn't seem pleased. I started to get uncomfortable at this point, why was I here?
The next thing he asked me to do was to look at the white board and write a formula and a program to print out a series of numbers: 1,2,3,10,36,490. (Not entirely sure on the last two) I stared at the board for awhile and nothing came to me so I started jotting things on the board. I was getting exasperated at this point and he finally asked if I wanted a hint. He asked if I knew what Fibonacci numbers were, and I asked him if it was related to the number pyramid (I meant pascal's triangle, which is directly related) but I just got the same look as before, which did not help matters in the events to come. He eventually assisted me to figure out the formula and told me to write the program.
I think at this point I had enough, and my mind was not cooperating. I tried writing the code and working through it with him but I was making mistakes and I couldn't think straight. I could tell he was getting frustrated. He finally stopped the interview and gave me a short lecture that they ask these questions to all their interviewees. That threatened my composure. I wasn't asked if I had any questions, he wanted me out of there pronto. Not a good feeling.
So in my opinion it was a fairly one-sided interview. Brush up on your mathematics (sequences and series) and practice writing code (including recursion) on a whiteboard while someone is silently watching you.