Even Mathworld/Weisstein's World of Mathematics isn't always right either. I found an error once, and sent it in (it was something to do with graph theory, and

Even Mathworld/Weisstein's World of Mathematics isn't always right either. I found an error once, and sent it in (it was something to do with graph theory, and the equation was missing a +1 or something, which was sort of critical). I checked about a month later and it hadn't been fixed, I can't remember what it was now, I really wish I could. It was something to do with "n/2 + 1" and they had written "n/2".