"The irrationality measure of $\pi$ as seen through the eyes of $\cos(n)$. A student asked: "What's the limit of $\cos(n)^n$?" Since it's always less than 1 in absolute value, as n becomes large, the result should go to zero. Except it doesn't. In fact, it "oscillates", because larger and larger fractions come closer and closer to approximating $\pi$. They go on to discuss qualitative irrationality, but that's more for specialists.
I suppose one conclusion to draw from this is: pay attention to student questions. Sometimes there's something weird hiding that nobody noticed before.
Drat. The article is too recent to qualify for the open access. I could read the paper in the library, but not from home. In order to cut down on the number of points, I didn't draw anything with abs() less than .01--pretend there's a line across the middle. Done with python, and I'm trusting that their $\cos$ function handles large numbers well.
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