In order to have a Regular Complementary Canon of Maximal Category we need rhythmic patterns having a 'good period'. The canon-n box acts as a sieve of Erathosten, according with the theory developed by Vuza (see the bibliography for more details). In this example we ask for 'good periods' in the interval between 0 and 500. Evaluate the canon-n box. Surprisingly enough, the smallest good period is 72.