problem Converging product Age 16 to 18 Challenge level In the limit you get the sum of an infinite geometric series. What about an infinite product (1+x)(1+x^2)(1+x^4)... ?
article Symmetric tangles The tangles created by the twists and turns of the Conway rope trick are surprisingly symmetrical. Here's why!
article An introduction to mathematical induction This article gives an introduction to mathematical induction, a powerful method of mathematical proof.