ABSTRACT
Th e following puzzle was aired on a local radio station as a contest: “Th ere is a well-known sequence represented by the three letters YTT. Th ere are several ways in which these letters can be replaced with another three letters so that it is still true, but only one way so that the new sequence looks similar to that starting one; it may be something like BAA. When can this happen?” Knowing that the answer to the radio contest was, “It can happen two days after this aired,” the question is, On which day was this puzzle aired on the radio?
