https://www.santantonio.org/en/content/tredicina-thirteen-day-novena

This term refers to the first thirteen days of preparation for the feast of St. Anthony, which takes place on June 13. The Tredicina is repeated again nowadays in the Basilica and in other Franciscan churches or Anthonian shrines, as well as in many families. The same term, however, is also used for a prayer consisting of “thirteen smaller prayers”, which highlight the most significant aspects of the Saint’s life and holiness. These prayers are recited alongside standard Catholic prayers.