The sequence of numbers 1,-24,252,-1472,4830,... was extensively studied by the great Indian mathematician Ramanujan a century ago. These numbers - the values of Ramanujan’s tau-function - have been the guiding force behind several themes in Number Theory. They continue to tantalize us with easy-to-understand problems some of which are still open today. Thistalk will be a relaxed introduction to these numbers and will lead up to some of our own results about them.